Cannabidiol use and effectiveness: real-world evidence from a Canadian medical cannabis clinic Open Access This article is licensed under a Creative Commons Attribution 4.0 International Public and medical interest in cannabidiol (CBD) has been rising, and CBD is now available from various sources. Research into the effects of low-dose CBD on outcomes like stress, anxiety, and sleep problems have been scarce, so we conducted an online survey of CBD users to better understand patterns of use, dose, and self-perceived effects of CBD. The sample consisted of 387 current or past-CBD users who answered a 20-question online survey. The survey was sent out to CBD users through email databases and social media. Participants reported basic demographics, CBD use patterns, reasons for use, and effects on anxiety, sleep, and stress. The sample (N = 387) consisted of 61.2% females, mostly between 25 and 54 years old (72.2%) and primarily based in the UK (77.4%). The top 4 reasons for using CBD were self-perceived anxiety (42.6%), sleep problems (42.5%), stress (37%), and general health and wellbeing (37%). Fifty-four per cent reported using less than 50 mg CBD daily, and 72.6% used CBD sublingually. Adjusted logistic models show females had lower odds than males of using CBD for general health and wellbeing [OR 0.45, 95% CI 0.30–0.72] and post-workout muscle-soreness [OR 0.46, 95%CI 0.24–0.91] but had higher odds of using CBD for self-perceived anxiety [OR 1.60, 95% CI 0.02–2.49] and insomnia [OR 1.87, 95% CI 1.13–3.11]. Older individuals had lower odds of using CBD for general health and wellbeing, stress, post-workout sore muscles, anxiety, skin conditions, focusing, and sleep but had higher odds of using CBD for pain. Respondents reported that CBD use was effective for stress, sleep problems, and anxiety in those who used the drug for those conditions. This survey indicated that CBD users take the drug to manage self-perceived anxiety, stress, sleep, and other symptoms, often in low doses, and these patterns vary by demographic characteristics. Further research is required to understand how low doses, representative of the general user, might impact mental health symptoms like stress, anxiety, and sleep problems. The cannabis compound known as CBD is being touted as a treatment for a variety of conditions. But the substance’s uncertain legal status is stalling serious investigation.
Cannabidiol use and effectiveness: real-world evidence from a Canadian medical cannabis clinic
Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
Cannabidiol (CBD) is a primary component in the cannabis plant; however, in recent years, interest in CBD treatments has outpaced scientific research and regulatory advancement resulting in a confusing landscape of misinformation and unsubstantiated health claims. Within the limited results from randomized controlled trials, and lack of trust in product quality and known clinical guidelines and dosages, real-world evidence (RWE) from countries with robust regulatory frameworks may fill a critical need for patients and healthcare professionals. Despite growing evidence and interest, no real-world data (RWD) studies have yet investigated patients’ reports of CBD impact on symptom control in the common expression of pain, anxiety, depression, and poor wellbeing. The objective of this study is to assess the impact of CBD-rich treatment on symptom burden, as measured with a specific symptom assessment scale (ESAS-r).
This retrospective observational study examined pain, anxiety, depression symptoms, and wellbeing in 279 participants over 18 years old, prescribed with CBD-rich treatment at a network of clinics dedicated to medical cannabis in Quebec, Canada. Data were collected at baseline, 3 (FUP1), and 6 (FUP2) month after treatment initiation. Groups were formed based on symptom severity (mild vs moderate/severe) and based on changes to treatment plan at FUP1 (CBD vs THC:CBD). Two-way mixed ANOVAs were used to assess ESAS-r scores differences between groups and between visits.
This retrospective observational study suggests CBD-rich treatment has a beneficial impact on pain, anxiety, and depression symptoms as well as overall wellbeing only for patients with moderate to severe symptoms; however, no observed effect on mild symptoms. The results of this study contribute to address the myths and misinformation about CBD treatment and demand further investigation.
Cannabidiol (CBD) is one of the primary cannabinoids found in significant but variable concentrations in cannabinoid-based medicines (CBM). While structurally similar to Δ9-tetrahydrocannabinol (THC), CBD does not cause intoxication or euphoria (Russo 2017) and has showed considerable tolerability in humans with a low abuse potential (Chesney et al. 2020). This favorable safety profile has led to the recent mitigation of legal and regulatory barriers surrounding purified CBD products in several countries and recent increased interest in CBD treatments. While recent rulings clarified that CBD is not a drug under the 1961 United Nations as Single Convention on Narcotic Drugs, regulatory status in the USA remains extremely confusing. When derived from cannabis, CBD is a schedule 1 drug but when derived from “industrial hemp” plants it may be lawful federally (Corroon and Kight 2018; Corroon et al. 2020). In Canada, CBD is controlled under the Cannabis Act as are all cannabinoids, cannabis, and cannabis-derived products (Canada Go 2021). This regulatory status imparts restrictions and access obstacles for researchers.
CBD is widely touted as a panacea for a wide range of health problems and has been marketed as a dietary and “wellness” product (Russo 2017; Khalsa et al. 2020; Eisenstein 2019). CBD’s potential effects as an add-on therapy have been studied for social anxiety disorders, schizophrenia, non-motor symptoms in Parkinson’s disease, and substance use disorders (Bergamaschi et al. 2011; Crippa et al. 2019; McGuire et al. 2018; Millar et al. 2019; Prud’homme et al. 2015; Thiele et al. 2019; Leehey et al. 2020). However, the evidence of its effectiveness for indications other than drug-resistant pediatric epilepsy conditions remains very limited (Larsen and Shahinas 2020; Franco et al. 2020) and safety considerations such as drug-drug interactions associated with unsupervised use remain (Chesney et al. 2020; Freeman et al. 2019). Randomized controlled trials (RCTs) are limited in their rigorous design, population sample, and duration of observation making generalization of results and long-term data scarce. Therefore, real-world evidence (RWE) provides valuable insights and supplemental information about the use, safety, and effectiveness of CBD-based treatments (Graham et al. 2020).
RWE from retrospective analyses and patient registries shows that CBMs are used for pain (chronic, neuropathic), mental health conditions, cancer-related symptoms (nausea, fatigue, weakness), HIV/AIDS, and neurological conditions (Bonn-Miller et al. 2014; Gulbransen et al. 2020; Lintzeris et al. 2020; Lucas and Walsh 2017; Sexton et al. 2016; Waissengrin et al. 2015). Symptom control is the primary reason for use of CBM, with most patients looking to address unalleviated symptoms, perceived symptom intensity, and burden on health-related quality of life independently of primary diagnosis (Sexton et al. 2016; Waissengrin et al. 2015; Baron et al. 2018; Purcell et al. 2019; Swift et al. 2005; Webb and Webb 2014). The Edmonton Symptom Assessment Scale-revised version (ESAS-r) is a validated scale to assess symptom burden developed for use in oncology and palliative care (Hui and Bruera 2017), it has relevance to medical cannabis care as patients are often treated for similar symptom management (Good et al. 2019; Pawasarat et al. 2020). Specifically, studies showed self-perceived improvement in ESAS-r emotional symptoms (anxiety and depression) scores following CBM treatment in oncology patients, while pain and wellbeing symptoms showed no improvement (Good et al. 2019; Pawasarat et al. 2020). Yet, RWE on CBD-rich products is scarce (Goodman et al. 2020; Shannon et al. 2019). In addition, although careful titration and treatment adjustment after initiation is critical to symptom improvement and adverse effects care, current literature has failed to address this issue.
In this study, we investigated treatment with CBD-rich products within a dedicated clinical setting in Quebec, Canada, and the effects on a very common clinical symptom expression of pain and comorbid anxiety and depression symptoms, as well as the effect on overall wellbeing. We also examined the relevant clinical effects that were observed when CBD-rich treatments were replaced by THC:CBD-balanced products at subsequent follow-up visits.
This study is a retrospective examination of patients who were prescribed CBD-rich products by physicians at a clinic dedicated to CBM treatments operating at four locations across Quebec, Canada. All data are collected as part of standard clinical procedures during the initial visit and during 3 (FUP1) and 6 (FUP2) month follow-up visits and extracted from electronic medical records (EMR) (Prosk et al., 2021). All data were anonymized following extraction from the EMR and no identifiers linking to original data were maintained. A waiver of consent was required and approved by Advarra Ethics Committee, who also approved the study protocol, and by the provincial privacy commission (La commission d’accès à l’information du Quebec).
Adult patients, at least 18 years of age, who were initially treated exclusively with CBD-rich products from 1 October 2017 to 31 May 2019 and for whom outcome scores and product information were recorded at FUP1 were included in this study. Patients were generally referred by primary-care physicians and specialists for an assessment on the suitability of medical cannabis to treat refractory symptoms. A complete medical history, including primary and secondary diagnoses, was collected at baseline visit. Medical cannabis treatment decisions are determined at the discretion of a clinic physician according to a standardized clinical procedure, including symptom identification, selection of product format, cannabinoid profile, and dosage based on existing evidence (MacCallum and Russo 2018; Cyr et al. 2018), but also to minimize risk of adverse effects. Patient and physician preference may also indicate initiation with products that have higher CBD and lower THC concentration in order to limit use of THC and its inherent potential adverse events. The follow-up visits serve to assess treatment compliance, safety, and effectiveness.
CBD-rich products in Canada
CBD-rich products are administered in various methods and formats, but most commonly as oral plant-derived extracts or oils and as inhaled dried flowers. In the Canadian medical cannabis program, CBD-rich cannabis oils contain approximately 0.5–1 mg of THC/mL and 20–25 mg of CBD/mL depending on the product manufacturer. Table Table1 1 provides cannabinoid content and THC:CBD ratio for the three most common oil products (over 85% of patients) authorized at the clinic. Furthermore, product details in this study sample are described in Table Table3. 3 . The clinic procedure dictates that all products with a ratio of CBD (mg) to THC (mg) higher than 10 are considered CBD-rich products.
THC and CBD contents and associated THC:CBD ratio for the three most common oil products authorized at the clinic
|CBD-rich products at baseline||THC:CBD-balanced products at FUP1||THC-rich products at FUP1|
|Authorized dose range (in ml/intake)||0.1–2||0.05–3||0.2–1.5|
|Oil (mg/ml)||THC||CBD||Ratio THC:CBD||THC||CBD||Ratio THC:CBD||THC||CBD||Ratio THC:CBD|
|Product 1||1.2||24||1:25||9.5||12||10:13||27.5||< 1||30:1|
|Product 3||< 1||20||1:20||10||13.5||10:13||26.3||< 1||30:1|
The data is categorized by product category: CBD-rich products, THC:CBD-balanced products, and THC-rich products
CBD cannabidiol, THC Δ9-tetrahydrocannabinol, SD standard deviation
Details of the THC and CBD component of the CBD-rich, the THC:CBD 1:1, and the THC-rich formulations
|CBD-rich products at baseline (n = 279)||THC:CBD-balanced products at FUP1 (n = 104)||THC-rich products at FUP1 (n = 12)|
|Oil products (in mg/ml)||0.1–2.0||2.0–52.0||0.6–30||2.5–39||1.25–45||0–18|
|Dried flower (in % w/w)||0.7||17.0||3.7–9||7.7–13.4||13–27||0–0.5|
|Average daily dose (mg)||0.5||11.47||19.65||26.32||54.28||10.80|
|Standard deviation (mg)||0.43||10.21||5.80||9.12||29.65||7.64|
|Maximum daily dose (mg)||6||156||60||78||90||54|
Data comes from our sample of 279 patients
CBD cannabidiol, THC Δ9-tetrahydrocannabinol
Treatment adjustments occur at follow-up visits as a result of lack of effectiveness, presentation of adverse effects, or social or economic barriers. Adjustments may include a change of the recommended CBD-rich product, method of administration, dosage, or a change in product formulation such as the introduction of THC:CBD-balanced or THC-rich products. We investigated the change from CBD-rich to THC:CBD products during FUP1 by forming two groups based on their product adjustment at FUP1 (CBD-rich vs THC:CBD). Products at FUP1 reflect those recommended at the visit. Therefore, the adjusted treatment affects only the evaluation at FUP2.
Patients age, sex, and diagnosis were recorded at baseline. Patients completed the ESAS-r (Edmonton Symptom Assessment System-revised version) at each visit. The ESAS-r is a self-administered scale, rating the severity of symptoms from 0 (absence of symptom) to 10 (worst possible severity) at the time of assessment (Hui and Bruera 2017). Symptoms evaluated include six physical- (pain, tiredness, nausea, drowsiness, lack of appetite, and shortness of breath), two emotional- (depression, anxiety), and one overall wellbeing-related symptoms. ESAS scores can be categorized as mild (score 0 to 3) moderate (score 4 to 6) or high (score 7 and above) (Butt et al. 2008) and the threshold for clinically significant improvement is a decrease of 1 point (Hui et al. 2015). Since pain and mental health issues represent the most common symptoms for patients and physicians seeking medical cannabis treatments, we investigated effects on pain, depression, and anxiety symptoms as well as overall wellbeing. For each symptom, two groups of patients were formed: moderate-severe severity group in which a baseline score of 4 or more was recorded and a mild severity group with baseline score of 0 to 3.
Mean scores and standard deviation (SD), as well as percentage, where appropriate are presented for each variable. All analyses were performed on each ESAS-r symptom separately through the data analytics software R v4.0.2. An initial analysis compared the overall ESAS-r scores between each visit no matter the severity of the group, and looked at the role of product group (CBD/THC:CBD vs CBD/CBD group) (between-factor). Tukey HSD post hoc test was used to confirm where the differences occurred between groups.
To determine whether CBD-based treatments have different effectiveness based on the severity of patient symptoms, two-way mixed ANOVAs with severity group as between-factor and visit as a within-factor were conducted to assess the change in ESAS-r scores between visits. Paired t-tests were subsequently performed to assess the difference in mean scores within each severity group between baseline and FUP1. Significant p value was set at 0.05 and all analyses were two-tailed. Partial eta-squared (η 2 p) are reported to indicate magnitude of differences between groups.
A total of 1095 patients were seen at the four clinic sites during the study period. Out of those, 715 were eligible for the study (at least 18 years old and initially treated exclusively with CBD-rich products). A total of 279 patients with ESAS-r scores and product information at FUP1 were analyzed (190 (68%) female, mean age = 61.1, SD = 16.6). The analyzed sample did not differ from the study-eligible group in terms of age, sex, or THC and CBD initial doses (all ps > 0.4). Table Table2 2 outlines patient sample size and demographic information for each symptom and treatment group. Two hundred and ten (75%) patients were prescribed CBD-rich products to treat chronic pain, 19 (7%) for cancer-related symptoms, 21 (7.5%) to treat neurological disorders (Parkinson’s disease, multiple sclerosis, and drug-resistant epilepsy among others), 8 patients for inflammatory disease (arthritis), 10 for gastrointestinal disorders (Chron’s disease, inflammatory bowel syndrome, ulcerative colitis), 2 for anxiety, 1 for depression, 2 for headaches, and 6 unclassified. The chronic pain category included all medical indications for which pain was the main symptom such as but not limited to fibromyalgia, spinal stenosis, and chronic low back pain. Overall, 116 (41.6%) patients adjusted their prescription by adding THC at FUP1 (either to a THC:CBD-balanced combination or a THC-rich treatment). Two hundred and three (73%) patients had moderate/severe ESAS-r scores on at least 2 of the examined symptoms, 57 (20%) on three, and 75 (27%) on all four symptoms. Twenty-nine (10%) patients report no moderate/severe symptoms; these people may use CBD for other ESAS-r symptoms not examined here (shortness of breath, tiredness, nausea, drowsiness, appetite). There was no statistical difference on either age, sex, or THC and CBD initial doses between the patients who completed one FUP versus those who completed two FUP (all ps > 0.1).
Demographic characteristics of 279 medical cannabis patients, by symptom group
|Sample size (percentage)||Number of female patients (percentage)||Mean age (SD)|
|Overall sample||279||190 (68)||61.1 (16.6)|
|Moderate or severe pain symptom group||205 (73.5)||150 (73)||61.8 (15.9)|
|Moderate or severe anxiety symptom group||138 (48.5)||97 (70)||61.43 (16.3)|
|Moderate or severe depression symptom group||115 (41.2)||81 (70)||60.5 (15)|
|Moderate or severe wellbeing group||202 (72.4)||141 (70)||60.8 (16.1)|
|CBD/THC:CBD group||116 (41.6)||75 (65)||60.38 (14.4)|
The symptom groups are mild and moderate or severe. The table presents the moderate or severe demographic characteristics. The CBD/THC:CBD group is composed of patients who added THC to their CBD-rich prescription during FUP1
CBD cannabidiol, THC Δ9-tetrahydrocannabinol, SD standard deviation
CBD-rich products characteristics
The baseline average daily doses for CBD and THC are presented in Table Table3. 3 . The maximum initial CBD dose recorded (156 mg) was prescribed for the treatment of pain of one patient. The maximum THC dose recorded at FUP1 (90 mg) was prescribed for two patients for the treatment of pain.
Outcome of CBD treatment
Mean ESAS-r scores of pain, anxiety, depression symptoms, and overall wellbeing at baseline, FUP1, and FUP2 are described in Table Table4 4 and Fig. Fig.1 1 .
Mean and standard deviation (SD) scores of ESAS-r scales for each severity group (mild or moderate/severe) and for each product group (CBD/CBD or CBD/THC:CBD)
|Baseline (sample size)||277||270||272||268|
|Overall sample||5.14 (2.57)||3.86 (3.19)||3.16 (3.08)||5.34 (2.61)|
|Mild severity group||1.69 (1.1)||0.99 (1.15)||0.87 (1.18)||1.86 (1.18)|
|Moderate or severe severity group||6.34 (1.7)||6.61 (1.78)||6.3 (1.86)||6.47 (1.83)|
|CBD/CBD group||5.03 (2.66)||3.80 (3.21)||2.99 (3.04)||5.28 (2.72)|
|CBD/THC:CBD group||5.28 (2.45)||3.95 (3.17)||3.40 (3.13)||5.42 (2.46)|
|FUP1 (sample size)||262||261||261||254|
|Overall Sample||4.37 (2.73)||2.93 (2.95)||2.33 (2.79)||4.45 (2.6)|
|Mild severity group||2.3 (2.4)||1.62 (2.08)||1.12 (1.78)||3.73 (2.75)|
|Moderate or severe severity group||5.04 (2.49)||4.15 (3.09)||3.77 (3.07)||4.72 (2.5)|
|CBD/CBD group||4.09 (2.67)||2.74 (2.87)||2.23 (2.71)||4.43 (2.6)|
|CBD/THC:CBD group||4.75 (2.78)||3.2 (3.05)||2.47 (2.9)||4.49 (2.63)|
|FUP2 (sample size)||101||99||102||97|
|Overall Sample||4.7 (2.7)||2.85 (3.01)||2.67 (3.02)||4.57 (2.47)|
|Mild severity group||2.18 (2.43)||1.32 (1.89)||1.52 (2.31)||3.82 (2.81)|
|Moderate or severe severity group||5.2 (2.47)||3.96 (3.19)||3.74 (3.26)||4.93 (2.23)|
|CBD/CBD group||4.55 (2.6)||2.44 (2.68)||2.44 (2.82)||4.76 (2.22)|
|CBD/THC:CBD group||4.88 (2.81)||3.08 (3.07)||2.94 (3.24)||4.36 (2.73)|
The CBD/THC:CBD group is composed of patients who added THC to their CBD-rich prescription during FUP1. ESAS-r scores varied between 0 and 10 for all assessed symptoms and all visits except for the anxiety scale at FUP2 for which the maximum score was 9
CBD cannabidiol, FUP1 follow-up visit at 3 month, FUP2 follow-up visit at 6 month, THC Δ9-tetrahydrocannabinol
CBD-rich treatment effectiveness on pain, anxiety, depression symptoms, and on overall wellbeing in 279 patients. FUP1, follow-up visit at 3 month; FUP2, follow-up visit at 6 month. Mixed ANOVAs revealed a significant effect of visit on symptom reduction between baseline and FUP1 but not between FUP1 and FUP2
All average ESAS-r scores decreased between baseline and FUP1 and FUP2. This was further demonstrated by ANOVAs which revealed a significant effect of visit on mean ESAS-r scores for each symptom assessed (pain: F(2,634) = 4.9, p < 0.008; anxiety: F(2,624) = 8.36, p < 0.001, depression: F(2,629) = 5.36, p < 0.004; wellbeing: F(2,613) = 8.31, p < 0.001; all η 2 p between 0.008 and 0.02). In all assessed symptoms, no significant main effect of adding THC at FUP1, nor visit-by-product interaction, were observed (all ps > 0.2). Post hoc tests revealed ESAS-r mean scores significantly decreased between baseline and FUP1 (all ps < 0.003) for all symptoms, between baseline and FUP2 for anxiety and wellbeing (both ps < 0.03), but not between FUP1 and FUP2 for any symptoms (all ps >0.5). This suggests statistical improvement recorded at FUP1 is still present at FUP2 in all symptoms independently from treatment adjustment at FUP1.
CBD treatment impact according to symptom severity
From Table Table2, 2 , moderate or severe scores at baseline were most common for pain (205 patients, 73.5%) and poor wellbeing (202 patients, 72.4%).
Clinical effect (difference of 1.3 to 2.5 points) observed in all symptoms for patients with moderate/severe symptoms between baseline and FUP1; however, there was no clinical effect for patients with mild symptoms (from − 0.3 to − 1.8) (Fig. (Fig.2). 2 ). No clinical effect was observed in any symptoms between FUP1 and FUP2 for patients with moderate/severe symptoms (− 0.4 to 0.5) as well as for patients with mild symptoms (from − 0.7 to 0.4).
CBD-rich treatment effect according to symptom severity: mild or moderate/severe in 279 patients. FUP1, follow-up visit at 3 month; FUP2, follow-up visit at 6 month. a Mean ESAS-r scores for the pain symptom, b mean ESAS-r scores for the anxiety symptom, c mean ESAS-r scores for the depression symptom, and d mean ESAS-r scores for overall wellbeing. According to mixed ANOVAs, patients with moderate/severe symptoms reported symptom reduction whereas patients with mild symptoms reported symptom deterioration from baseline to FUP1. No effect was statistically significant between FUP1 and FUP2
The ANOVA revealed that all main and interaction effects were significant at the 0.001 level with effect sizes large for severity (η 2 p = 0.29), medium for visit (η 2 p = 0.06), and small for the interaction (η 2 p = 0.03). Post hoc tests revealed a significant score difference between baseline and FUP1 and FUP2 (both ps < 0.05) but not between FUP1 and FUP2 (p = 0.98). Patients with moderate/severe symptoms on pain experienced important improvement at FUP1 (t(194) = 7.61, p < 0.001) whereas ESAS-r scores for patients with mild symptoms actually increased (t(64) = − 2.03, p < 0.05) (Fig. (Fig.2 2 a).
There were significant effects of visit, severity group, and visit by group interaction (all ps < 0.001; η 2 p = 0.006, η 2 p = 0.4, η 2 p = 0.1, respectively). Post hoc tests revealed a significant score difference between baseline and FUP1 and FUP2 (both ps < 0.001) but not between FUP1 and FUP2 (p = 0.38). Although there was a large improvement for patients with moderate to severe anxiety symptoms (t(131) = 9.36, p < 0.001), the anxiety scores of patients with mild symptoms increased (t(119) = − 3.19, p < 0.01) from baseline to FUP1 (Fig. (Fig.2 2 b).
The ANOVA showed main effects of visit, severity group (both ps < 0.001 with η 2 p = 0.04 and η 2 p = 0.4, respectively) and a significant group-by-visit interaction (F(2,620) = 34.47, p < 0.001; η 2 p = 0.1). Post hoc tests revealed a significant score difference between baseline and FUP1 and FUP2 (both ps < 0.01) but not between FUP1 and FUP2 (p = 0.85). Specifically, the scores of moderate/severe group decreased notably (t(110) = 9.56, p < 0.001) between baseline and FUP1 but the scores of the group with mild depression symptoms did not (p = 0.07) (Fig. (Fig.2 2 c).
The ANOVA showed main effects of visit, severity group (both ps < 0.001 with η 2 p =0.04 and η 2 p =0.3 respectively) and a significant group-by-visit interaction (F(2,597) = 36.53, p < 0.001; η 2 p = 0.11). Post hoc tests revealed a significant main score difference between baseline and FUP1 and FUP2 (both ps < 0.01) but not between FUP1 and FUP2 (p = 0.89). Precisely, the scores of the group reporting good wellbeing increased (t(182) = 8.8, p < 0.001) whereas scores of patients with worst wellbeing notably decreased (t(59) = − 5.08, p < 0.001) between FUP1 and FUP2 (Fig. (Fig.2 2 d).
This retrospective study explored the use of CBD-rich products in a medical cannabis clinical setting in Canada and associated effectiveness on a common symptom cluster presentation of pain, anxiety, depression, and poor sense of wellbeing, as measured by ESAS-r.
Patients treated with CBD-rich products were mainly women in their sixties, seeking predominantly chronic pain management.
Our findings show that overall effectiveness of CBD treatment is primarily by patients with moderate to severe symptoms. A deficiency in the endocannabinoid system (ECS) may provide a possible explanation for this result (Russo 2016). The ECS could be more deficient in patients with moderate/severe symptoms compared to mild symptoms leading to increased improvement in the first group. The absence of significant improvement for patients with mild symptoms at baseline may be explained by a smaller margin for symptom improvement. In such patients, CBD treatments may have been targeted to other clinical symptoms not assessed in the current study. There is a probable placebo effect; however, there were no differences in initial CBD doses between the severity groups. Furthermore, associated placebo effect would likely be decreased by FUP3M, also considering the significant treatment cost. The distinct beneficial impact of CBD treatment observed for patients with moderate-severe symptoms could elucidate discrepancies found in the literature.
RCTs on CBM and pain symptoms provide inconclusive results; however, several report that treatments of THC and CBD have some benefit for pain management (Häuser et al. 2018; Russo 2008; Prosk et al. 2020). Our results are largely novel as research on the effect of CBD on pain control is very limited (Boyaji et al. 2020). The reduction in reported anxiety may also contribute to the improvement in pain perception.
Discrepancies still exist regarding the anxiolytic effect of CBD. Some RCTs indicate an anxiolytic effect of CBD upon experimentally induced scenarios (Bergamaschi et al. 2011; Zuardi et al. 2017; Bhattacharyya et al. 2010; Skelley et al. 2020); however, these findings are difficult to replicate (Larsen and Shahinas 2020; Hundal et al. 2018; Crippa et al. 2012). This reinforces our findings that CBD may have a differential effect depending on anxiety severity. Regarding the effects of CBD on depression symptoms, further research is required to draw conclusions (Khalsa et al. 2020; Schier et al. 2014; Turna et al. 2017).
The addition of THC to CBD during FUP1 did not produce any effect on ESAS-r scores at FUP2 in this analysis; however, the magnitude of the difference between groups is small. The examination of treatment regimen has been seldom addressed in the literature and further development is required to inform guidelines for prescription and refinement of clinical practice.
Furthermore, a significant discrepancy is observed between the recorded dosages of oral CBD in RCTs and dosages in real-world settings. The average daily CBD dosage authorized at our clinic (11.5 mg) is closer to other observational studies (Gulbransen et al. 2020) compared to what is seen in RCTs (up to 1000 mg for a single dose) (Larsen and Shahinas 2020). The presence of THC and other cannabinoids in CBD-rich products may affect the outcomes in this study. The majority of RCTs investigated single-dose administration of CBD making it difficult to compare observed treatment outcomes with chronic dosing clinical settings. Importantly, medical cannabis products are generally not covered by most insurers and patients rely on out-of-pocket payments. The cost of CBD remains very high globally, approximately $CAD 5–20 per 100 mg (Canada Go 2021; Eisenstein 2019; Canada 2020). Availability of reliable cannabinoid testing in certain international jurisdictions is also limited. The gap between effective doses demonstrated in RCTs and the actual affordable doses demonstrated by RWE mandate the need for a precise pricing and marketing strategy at the initiation of any drug development process.
Limitations are common in real-world data (RWD), especially in retrospective studies. In this study, with no control group, no causality effect can be drawn between CBD-rich treatment and symptom improvement. Most patients treated with CBM present with multiple severe symptoms and the analyses presented here are limited to identify the treatment outcomes for such patients. Further studies can investigate the use of CBD to treat several symptoms simultaneously.
The self-reported subjective assessment used may be biased by the patient’s positive expectation of treatment, which could lead to a possible placebo effect. This perceived effectiveness bias may also be increased by social and economic barriers. The current context of medical cannabis access, including social stigma, high cost, and lack of universal insurance coverage can increase the patient selection bias. Self-selection bias is increased by the significant patient interest in medical cannabis as these patients must be motivated to access the non-traditional medication system. This bias limits the generalizability of results but is common across international medical cannabis regimens and should not discount the observed results. The heterogeneity of the patient population with a variety of diagnoses and the diversity of medical cannabis preparations also affects the external validity of the study. However, clinical findings from within Canada’s controlled regulatory program do provide important models for international consideration. Future research is required in controlled clinical settings to examine these factors in order to provide a more complete account of CBD effectiveness.
Also, there was a large drop of sample size (53% loss) due to missing data. Additionally, there was an important loss to follow-up at the 6-month visit (FUP2) due to missed appointment and cost barriers, limiting the power of the findings. The total treatment cost has significant impact on treatment continuation. Improved patient retention and more robust, harmonized data collection methods will improve future observational studies and allow for long-term assessment. Collection of detailed, accurate product information is a challenge, especially with inhaled products (Corroon et al. 2020). There are opportunities for administration devices and other technology advancements to improve this limitation. Lastly, this study did not include safety data assessment, future studies should investigate safety considerations of CBD (Chesney et al. 2020). Collection of high-quality RWD will require improvements in patient retention, data monitoring, and more robust data collection methods within a controlled clinical setting.
This study on CBD-rich products demonstrates the potential of RWE for the advancement of medical cannabis research and practice guidelines, especially in a world where CBD use is exponentially increasing but scientific data are limited. It revealed that CBD-rich treatments have a beneficial impact on patients with self-reported moderate or severe symptoms of pain, anxiety, or depression and overall wellbeing but not in patients with mild symptoms. Further investigation is clearly required, but as of now the hyped, and often illegal, marketed claims of CBD as a wellness product are unsubstantiated. Our findings have important and novel implications to clinical practice, especially the examination of treatment plan adjustment during the first follow-up after initiation with CBD treatments. Improvements in access regimes, oversight, and clarification from regulatory agencies are also needed to improve the validity of RWE and assessment of the use of CBD-rich products.
The authors would like to thank the participants to this study. The authors would like to acknowledge Santé Cannabis co-founder Dr. Michael Dworkind and key clinical leaders Dr. Antonio Vigano, Dr. Howard Mitnick, Dr. Alain Watier, and Youri Drozd, clinical data assistant, for his contribution to data technical help.
|EMR||Electronic medical record|
|ESAS-r||Edmonton Symptom Assessment System-revised version|
All authors contributed to conception and design, interpretation of data, manuscript writing, and final approval. LR and RG conducted the analysis of data. All authors agreed to be accountable for their own contributions. The author(s) read and approved the final manuscript.
This research was funded internally by Santé Cannabis clinic.
Availability of data and materials
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
A waiver of consent was required and approved by Advarra Ethics Committee, who also approved the study protocol, and by the provincial privacy commission (La commission d’accès à l’information du Quebec).
L.R.: Clinical research associate, employee at Santé Cannabis.
R.G.: Epidemiologic and statistic consultant for Santé Cannabis.
C.EH.: Director of Research and Innovation, employee at Santé Cannabis.
MF.A.: Associate Research Director of Santé Cannabis.
E.P.: President and co-founder of Santé Cannabis.
Santé Cannabis is a medical clinic, research, and training center dedicated to medical cannabis. The views expressed are those of the authors. This is a retrospective, observational study which took place at Santé Cannabis; therefore, the design and conduct of the study was executed by Santé Cannabis clinic staff. C.EH. and E.P. had a supporting role, in the retrospective protocol development. The authors had no role in the conduct of the study and collection of data. None of the authors are involved in the care of patients or in treatment decisions. The authors acted independently, and Santé Cannabis had no role in the analysis of the study, nor the writing of the manuscript or decision to publish. There is no financial gain for Santé Cannabis or for the authors to publish. The authors, while connected to Santé Cannabis, do not have a financial or professional incentive for the decision to publish.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Reasons for cannabidiol use: a cross-sectional study of CBD users, focusing on self-perceived stress, anxiety, and sleep problems
Public and medical interest in cannabidiol (CBD) has been rising, and CBD is now available from various sources. Research into the effects of low-dose CBD on outcomes like stress, anxiety, and sleep problems have been scarce, so we conducted an online survey of CBD users to better understand patterns of use, dose, and self-perceived effects of CBD.
The sample consisted of 387 current or past-CBD users who answered a 20-question online survey. The survey was sent out to CBD users through email databases and social media. Participants reported basic demographics, CBD use patterns, reasons for use, and effects on anxiety, sleep, and stress.
The sample (N = 387) consisted of 61.2% females, mostly between 25 and 54 years old (72.2%) and primarily based in the UK (77.4%). The top 4 reasons for using CBD were self-perceived anxiety (42.6%), sleep problems (42.5%), stress (37%), and general health and wellbeing (37%). Fifty-four per cent reported using less than 50 mg CBD daily, and 72.6% used CBD sublingually. Adjusted logistic models show females had lower odds than males of using CBD for general health and wellbeing [OR 0.45, 95% CI 0.30–0.72] and post-workout muscle-soreness [OR 0.46, 95%CI 0.24–0.91] but had higher odds of using CBD for self-perceived anxiety [OR 1.60, 95% CI 0.02–2.49] and insomnia [OR 1.87, 95% CI 1.13–3.11]. Older individuals had lower odds of using CBD for general health and wellbeing, stress, post-workout sore muscles, anxiety, skin conditions, focusing, and sleep but had higher odds of using CBD for pain. Respondents reported that CBD use was effective for stress, sleep problems, and anxiety in those who used the drug for those conditions.
This survey indicated that CBD users take the drug to manage self-perceived anxiety, stress, sleep, and other symptoms, often in low doses, and these patterns vary by demographic characteristics. Further research is required to understand how low doses, representative of the general user, might impact mental health symptoms like stress, anxiety, and sleep problems.
In the past years, cannabidiol (CBD), one amongst hundreds of naturally occurring phytocannabinoids found in the Cannabis sativa plant, has received a lot of attention from scientific communities, politicians, and mainstream media channels. CBD is the second most abundant cannabinoid in the Cannabis sativa plant after delta-9-tetrahydrocannabinol (THC), but unlike THC, CBD is not intoxicating (Pertwee 2008). In many countries, including the UK, there is unsanctioned availability of products containing CBD, from oils and capsules to chewing gums, mints, soft drinks, gummies, and intimate lubrication gels.
CBD has not demonstrated any potential for abuse or dependency and is considered well tolerated with a good safety profile, according to a report released by the World Health Organization (WHO) (Geneva CANNABIDIOL (CBD) n.d.). Since January 2019, the European Union (EU) has classified CBD as a novel food, implying that before 1997, consumption was insignificant. Each country has implemented the regulation of CBD differently. In the UK, The Food Standards Agency (FSA) recommends limiting the daily dose of CBD to 70 mg (Cannabidiol (CBD) n.d.). However, researchers have used doses up to 1200 mg without serious side-effects (Davies and Bhattacharyya 2019). Conversely, few clinical trials involving children with treatment-resistant epilepsy who received either 10 or 20 mg/kg of CBD (Epidiolex) for 12 weeks recorded side-effects, such as a reversible rise in liver enzymes (Devinsky et al. 2018a; Thiele et al. 2018).
The popularity of CBD can be partly explained by an increasing number of preclinical and clinical studies indicating a range of potential health benefits. However, mass media interest also plays a significant role. Studies suggest CBD might help with mental health symptoms and neurological conditions like experimentally induced anxiety (Zuardi et al. 1993), generalised social anxiety disorder (Bergamaschi et al. 2011), social phobia (de Faria et al. 2020), and conditions like PTSD (Elms et al. 2019; Shannon and Opila-Lehman 2016) schizophrenia (Zuardi et al. 2006; Leweke et al. 2012; Morgan and Curran 2008; Schubart et al. 2011), addiction (Hurd et al. 2019; Hindocha et al. 2018; Galaj et al. 2020), and epilepsy (Devinsky et al. 2017; Devinsky et al. 2018b; Cunha et al. 1980). These mental health disorders are often co-morbid and include other symptoms CBD might help with, e.g. sleep and impaired cognition. There is also data to suggest CBD could help treat neurodegenerative diseases like Alzheimer’s disease (Watt and Karl 2017; Fernández-Ruiz et al. 2013; Esposito et al. 2006), Parkinson’s disease (Fernández-Ruiz et al. 2013; García-Arencibia et al. 2007), and chronic pain conditions including fibromyalgia (Van De Donk et al. 2019), either alone or with THC (Rog et al. 2005; Berman et al. 2004; Wade et al. 2003; Svendsen et al. 2004; Notcutt et al. 2004). Additionally, in more than 30 countries, health authorities have approved CBD, under the name Epidiolex, to treat two severe forms of treatment-resistant childhood epilepsy (Dravet and Lennox-Gastaut syndrome) (Devinsky et al. 2016; Silvestro et al. 2019). Sativex, a sublingual spray containing an equal amount of THC and CBD, is also approved to treat multiple sclerosis in more than 30 countries (Keating 2017).
When used in high doses, somnolence is a primary adverse effect (Machado Bergamaschi et al. 2011). Patients in CBD clinical trials were more likely to experience sedation (OR 4.21, 95% CI 1.18–15.01) and somnolence (OR 2.23, 95% CI 1.07–4.64) in comparison to placebo (Chesney et al. 2020). Despite this preclinical and experimental research, there is a lack of human clinical trials to establish the efficacy and appropriate CBD indications fully. The effective dose for most of the above indications is still to be determined. In much of the research, high doses of CBD are used (between 300 and 1200 mg), whilst at the same time, globally, millions of CBD users are using low dose CBD. Thus, a disconnect exists between clinical research and the current state of the market.
A cross-sectional study of 2409 cannabidiol users from the USA found that the top three medical conditions reported were chronic pain, arthritis/joint pain, and anxiety, followed by depression and insomnia (Corroon and Phillips 2018). A recent survey carried out by Wheeler et al. of 340 young adults, some of whom were CBD users, found the top reasons to be stress relief, relaxation, and sleep improvement. They found edible CBD products to be the most prevalent (Wheeler et al. 2020). Another study of 400 CBD patients in New Zealand observed an increase in overall quality of life, a decrease in perceived pain, depression, and anxiety symptoms, as well as an increase in appetite and better sleep (Gulbransen et al. 2020).
A national survey indicated that in the UK, 8–11% of the adult population had tried CBD by June 2019 (Andrew et al. 2019). Studies of Google searches have shown considerable increases in CBD interest, with 6.4 million unique searchers in the USA in April 2019 (Leas et al. 2019). Yet it is clear that scientists, physicians, and governments were not prepared for the rapid surge in CBD use.
The regulatory confusion, along with recent media hype, has made it hard for most people to understand the true nature of CBD. Being classified as both a medicine and a supplement in some forms, whilst an illegal substance in others leads to consumer and patient confusion and potential frustration. Therefore, this study aimed to understand users’ consumption patterns regarding dose, route of administration, and reasons for using CBD. We hypothesised that out of all reasons for using CBD, the top three would be anxiety, sleep disturbances, and stress.
We developed an anonymous online questionnaire to collect CBD users’ self-reported characteristics, preferred method/s, and reason/s for using CBD. The survey was hosted on Survey Monkey Inc. (San Mateo, CA, USA). Data was collected between 10 January 2020 and 18 March 2020. The 20 questions were designed as multiple-choice questions with the option to choose either one or more answers. For some questions, respondents could write an alternative response if no option matched. We collected demographic information (age, sex, and location), CBD use patterns, reasons for use, other medication use, perceived effects, and side effects. The full questionnaire is provided in the supplementary materials.
To access actual CBD users, we collaborated with four different CBD brands and retailers (TheDrug.Store, OTO CBD, With Pollen and Grass & Co.), based in the UK, who sent out the survey to their email databases. The survey was sent out to 14,743 unique email addresses. Two thousand five hundred thirty-four were opened and 475 clicked through to the survey. We also shared the survey with CBD user groups on social media channels like Facebook and LinkedIn. We did not collect any personal data or IP addresses. Ethical approval was not required since this research investigated non-sensitive information using anonymous survey procedures with participants not defined as “vulnerable”. In addition, participation was deemed unlikely to induce undue psychological stress or anxiety based on ethics committee guidelines (UCL REC n.d.).
All analyses were conducted in SPSS version 24 (IBM Corporation, Armonk, NY). Valid percentages are reported rather than absolute values for descriptive statistics to account for missing data. We only report data on those reporting using CBD themselves equivalent to 90% of the respondents (e.g., not for veterinary use, not those who had not tried it, and those reporting on behalf of other users). An analysis of non-responders can be found in supplementary materials. We conducted logistic regression models to investigate associations between sex (males [reference category] and females), age (recoded to < 34 years old [reference category], between 35 and 54 years old, and 55+) and location (UK [reference category], other). For CBD use patterns, we used separate models to compare those who did and did not report their primary use of CBD for self-perceived anxiety, stress, and sleep whilst controlling for sex, age, and location. We dummy-coded “time of day” as each category versus all others. We report adjusted odds ratios with 95% confidence intervals and p values with a defined cut-off of 0.05.
The most significant findings were that many CBD users reported that CBD could improve sleep problems, stress, and anxiety and be used for general health and wellbeing. In the detailed results below, you can find the demographics of our survey population (Table 1), the CBD use patterns (Table 2), and logistic regression and OR’s for the different subgroups. The indications for CBD use are shown (Fig. 1), as well as how CBD affects sleep (Fig. 2), and other effects of CBD (Fig. 3). Using CBD for sleep was associated with taking it in the evening, and using CBD for anxiety or stress was associated with the sublingual route. Females had higher odds of using CBD for anxiety and men for post-workout. Details of the results can be found below.
Reasons for cannabidiol use amongst 397 adult cannabidiol users who were allowed to respond to more than one option leading to a total of 1622 responses. Y-axis represents percentage based on total responses
Perceived effects of cannabidiol on sleep amongst adult cannabidiol users responding to the question “how does cannabidiol affect your sleep?” Participants were allowed to select multiple options. Y-axis represents percentage of total responses (n = 522)
Other perceived benefits of cannabidiol amongst adult cannabidiol users. Respondents were asked what other benefits or effects they feel from using cannabidiol. Participants were allowed to select multiple options. X-axis is the percentage of total responses (n = 906)
A total of 430 people started the survey, of whom 15 (3.48%) did not respond to any questions, and 28 (6.5%) reported they did not use CBD themselves (analysis of these non-users can be found in the supplementary materials). Non-CBD-users skipped most questions and had sociodemographic characteristics similar to those of CBD users. Three hundred eighty-seven (90%) reported using CBD themselves. The majority of users were females from the UK (see Table 1). In regards to other medication use, there were a total of 467 responses. 39.4% of respondents reported not taking any other medication, 14.7% “painkillers”, and 14.7% “other” (40% anxiolytics and antidepressants). No other medication was reported by more than 10% of responses.
Logistic regression on location purchased (CBD shop or other) found that those who lived outside of the UK (aOR 2.286, [95% CI 1.35–3.86], p = 0.002) and males (aOR 1.75, [95% CI 1.06–2.88], p = 0.02) had greater odds of purchasing CBD from an “other” location. Each of the primary disorders was included in the model individually, and did not significantly alter the model and were not associated with location purchased.
CBD use patterns
The majority of users take CBD sublingually for 3–6 months (see Table 2). Those 35–54 years old (aOR 1.67 [95% CI 1.02–2.72], p = 0.04) and those 55+ (aOR 2.01, [95% CI 1.11–3.64], p = 0.02) had greater odds of using CBD daily in comparison to less than daily. There were no associations with self-perceived anxiety, stress, or sleep improvement. Females had lower odds of using CBD for greater than 1 year versus less than 1 year (aOR 0.54, [95% CI 0.38–0.88], p = 0.013) suggesting females had used CBD for less time. No associations emerged for self-perceived anxiety, stress, or sleep. There were no sex or age associations for the frequency of use, duration of use, or number of times per day. Females had a greater odds of responding that they take CBD when they need it versus males (aOR 1.79, [95% CI 1.036–3.095], p = 0.037). However, no other associations with age and sex on time of day emerged.
Compared with people not using CBD for anxiety, those who did self-medicate used CBD multiple times a day (aOR 3.44, [95% CI 1.70, 7.00], p = 0.001). Moreover, compared with those not using CBD for self-perceived stress, those who were self-medicating also used CBD multiple times a day (aOR 1.97, [95% CI 1.034–3.77], p = 0.039). Those using CBD for sleep improvement had greater odds of using CBD in the evening (aOR 3.02, [95% CI 1.86, 4.93], p ≤ 0.001) and lower odds of using CBD in the morning (aOR 0.157, [95% CI 0.07–0.38], p ≤ 0.001). Those using CBD for self-perceived anxiety had lower odds of using CBD in the evening (aOR 0.56, [95% CI 0.14–0.45], p ≤ 0.001). No associations emerged between those who did and did not use CBD for self-perceived stress on the time of day they used CBD.
CBD dose and route of administration
Route of administration did not vary by sex. There were lower odds of those aged 55+ of vaping CBD (aOR 0.176, [95% CI 0.04–0.80], p = 0.025) as well as lower odds of those aged 35–55 (aOR 0.245, [95% CI 0.10–0.59], p = 0.002) and 55+ (aOR 0.115, [95% CI 0.025–0.520], p = 0.005) in comparison to 18–34 years old for drinking CBD. Self-reported anxiety (aOR 1.78, [95% CI 1.08–2.92], p = 0.023) and those using CBD for sleep improvement (aOR 1.945, [95% CI 1.152–3.285], p = 0.013) were associated with the sublingual route. Stress was not associated with route of administration.
Reasons for use of CBD
42.6% endorsed using CBD for self-perceived anxiety, followed by 37.5% for stress, 37% for general health and wellbeing, and 37% for improving sleep (see Fig. 1). 24.6% reported use for self-perceived insomnia. Overall, 42.5% of respondents said they were using CBD for some sleep issue, either to improve sleep or for self-perceived insomnia. In the supplementary materials (see Table 2), we show reasons for use broken down by sex, age, and location.
In adjusted logistic models, more males (47.4%) were using CBD for general health and wellbeing than females (30.7%; aOR 0.464, [95% CI 0.30–0.72], p = 0.001). More females were using CBD for self-perceived anxiety (47.9%) than males (34.2%; aOR 1.595, [95% CI 1.021, 2.49], p = 0.04), and for self-perceived insomnia (females 28.6%, males 17.8%; aOR 1.871, [95% CI 1.125–3.112], p = 0.015). More males (14.1%) than females (7.1%) were using CBD for post-workout sore muscles (aOR 0.462, [95% CI 0.236–0.905], p = 0.024).
One hundred sixty-five of 387 (42.6%) endorsed using CBD for self-perceived anxiety. In response to the question “how does CBD affect your anxiety levels”, participants responded that they felt less anxious (141/163 (86.5%)), followed by “no difference (I still suffer from the same degree of anxiety)” (21/163; 12.8%), and one person (0.6%) noted greater anxiety. Moreover, participants were asked how often they thought about problems when they were supposed to be relaxing, compared with before they started taking CBD. We found that just 96/163 (58.9%) of respondents thought about their problems less than before, followed by “it hasn’t changed (I still think a lot about problems” (55/163; 33.7%), followed by “it hasn’t changed (I did not think about problems a lot before)” (11/163; 6.7%), followed by (1/163; 0.6%) of respondents reporting thinking about problems more than before.
Amongst those who reported experiencing anxiety, adjusted logistic models comparing those who responded that CBD reduces their self-perceived anxiety with those who responded that they still suffer from anxiety found no associations with age, sex, or location. Similar results emerged for “thinking about problems”.
One hundred forty-five of 387 (37.5%) of respondents endorsed the use of CBD for self-perceived stress. Amongst those using CBD for stress, in response to the question “how does CBD affect your stress level”, participants responded that they felt less stressed (130/141; 92.2% followed by it does not affect my stress levels (I still feel stressed) (11/141; 7.8%). No respondent said that it increased their stress level. Adjusted logistic models comparing those who responded that CBD reduces their stress versus those who responded that they still have stress found no associations with age, sex, or location.
Self-perceived sleep problems
As we initially designed the study to address sleep, we asked detailed questions regarding this. Improving sleep (125/387; 32.3%) and self-perceived insomnia (95/387; 24.5%) were the fourth and fifth-ranked endorsed reasons for using CBD, overall 42.5% endorsed sleep as a reason for use. Respondents said that CBD helped them sleep (see Fig. 2). As we restricted this analysis to respondents who selected using CBD for sleep improvement, there was considerable overlap between using CBD for sleep improvement and self-perceived insomnia. Regarding questions about the time it takes to fall asleep, 48.2%(73/124;) said CBD led them to fall asleep faster, followed by 29/124 (23.4%) who said it did not make a difference and still have a hard time falling asleep, followed by 22/124 (17.7%) who said it did not make a difference because they did not have a problem falling asleep beforehand. Age, sex, and location were not associated with the speed of falling asleep.
Other reported benefits
We asked participants to report on other effects they experience. From a total of 960 responses, the most prevalent effect was calm (21.3%), followed by decreased pain (19.5%) (see Fig. 3). One per cent reported feeling euphoric/high. In examining the “other” responses, 27/960 (9.3%) reported that they did not feel any benefits from the use of CBD.
Sex was associated with sexual enhancement where males reported experiencing more sexual enhancement (9.9%) than females (2.9%) (aOR 0.274, [95% CI 0.11–0.70], p = 0.007). There were no other associations between sex and other CBD benefits. Those aged 55+ (23.1%; aOR 3.8, [95% CI 1.63–8.87], p = 0.002) and those aged 35–54 years old (16.8%; aOR 2.72, [95% CI 1.258–5.876], p = 0.011) reported taking less of their other medications in comparison to those aged under 34 years old (9.9%). Those ages 55+ reported experiencing more “no positive experiences” (14.3%) in comparison to those under 34 (2.7%; aOR 5.31, [95% CI 1.45–19.41], p = 0.012).
A total of 388 responses were made, of whom 277/388 (71%) were logged as not experiencing any side-effects. Dry mouth was experienced by 44/388 (11%), and 13/288 (3%) experienced fatigue. All other side-effects were reported less than 2% (e.g. dizziness, nausea, upset stomach, rapid heartbeat, diarrhoea, headache, anxiety, psychotic symptoms, sexual problems, trouble concentrating). No respondents reported vomiting, fainting, liver problems (raised liver enzymes in blood test), or seizures. Adjusted logistic models show no associations of age, of sex with “no side effects” or fatigue. Location of the participants was associated with dry mouth, those who lived outside of the UK had greater odds of experiencing dry mouth (aOR 2.44, [95% CI 1.25–4.75], p = 0.009). No other side-effects were analysed due to the small number of respondents citing other side-effects.
This study aimed to investigate CBD use patterns in the general population regarding the route of administration, dose, and indications for use. We found that the main indications for using CBD were self-perceived anxiety, stress, general health and wellbeing, sleep, and pain.
User characteristics and reason for use
More than half of the users were using a daily dose below 50 mg via a sublingual route of administration. Most were using CBD daily, sometimes multiple times per day. We found that respondents who use CBD for self-perceived anxiety and stress tend to use it several times per day, whilst respondents endorsing using CBD for sleep take it in the evening, indicating that user patterns vary according to the symptoms. A recent review suggests half-life is between 1.4 and 10.9 h after oromucosal spray and 2–5 days after chronic oral administration (Iffland and Grotenhermen 2017). In the light of these findings, it may be that people are dosing CBD several times per day to maintain stable plasma levels throughout the day if managing symptoms of stress and anxiety, whilst only using CBD at night if managing sleep problems.
We found that 69.7% of users had been using CBD for less than 1 year. Moreover, only 4.1% had used CBD for more than 5 years, reflecting both that it is a fairly new phenomenon and an increasing interest in CBD in the UK, compared with the USA. A similar American survey reported that 34.6% had used CBD for less than 1 year and 53.2% more than 5 years (Corroon and Phillips 2018). At the time of writing, CBD is legal in all but three, out of fifty, American states, and many of these allow the products to contain THC. In the UK and Europe, non-prescription CBD products are not allowed to contain any THC (< 0.01%). These differences might create a divergence between European vs American consumers’ experiences, and stresses the urgency for internal and external regulation, and education about cannabinoids in Europe.
We found age and sex differences in the reason for CBD use. Most of the sample was female, but males had greater odds of using CBD for general health and wellbeing and post-workout for sore muscles. In contrast, females were more likely to use CBD for self-perceived anxiety and insomnia, reflecting the higher prevalence of both symptoms amongst women (McLean et al. 2011; Li et al. 2002). We also found more females using CBD for fibromyalgia, possibly reflecting the much higher prevalence of fibromyalgia amongst women (Yunus 2002). A recent study compared the subjective effects of 100 mg oral versus vaporised and smoked CBD and found that women reported experiencing more subjective effects of CBD than men (Spindle et al. 2020), which may reflect why women were using CBD for more chronic symptomology. There were also significant age differences, with more people under 34 years old using CBD for general health and wellbeing than older age groups, which might be explained in part by the fact that disease burden generally increases with age. More young people use CBD to reduce self-perceived stress and anxiety, aligning with studies finding young people are more troubled by symptoms of anxiety than older people (Brenes et al. 2008).
In the present study, we found that the largest proportion of respondents used CBD to help with mental health symptoms like perceived anxiety, stress, and sleep problems. This finding aligns with a previous CBD survey that found that anxiety and insomnia were amongst the top 6 reasons for using CBD (Corroon and Phillips 2018). However, Corroon et al. found that the two main reasons for using CBD was arthritis/joint pain and chronic pain, whereas these ranked number six and seven amongst reasons from our respondents. This result may reflect the younger demographics of our sample compared with Corroon et al.
With few variations, the reasons for use in our study were somewhat similar to the results from another study of 400 patients in New Zealand, who were all prescribed sublingual CBD oil with doses ranging from 40 to 300 mg/day (Gulbransen et al. 2020). This study found that the patients had an increase in overall quality of life, including improved sleep and decreased self-perceived anxiety levels and reduced pain scores.
Route of administration, dosing, and side-effects
Younger respondents were more likely to use novel routes of administration, e.g., vaping or drinking. This trend correlates with data showing that more people have tried vaping (in general) amongst younger age groups (Vaping and e-cigarette use by age U.S 2018). Only 9.3% reported vaping CBD in our sample, compared with 19% in the study by Corroon et al. (Corroon and Phillips 2018). The fast onset of vaporised CBD might explain why inhaled CBD is popular for self-perceived anxiety and stress.
Corroon et al. found a more even distribution between various application methods with the most popular being sublingual CBD (23% vs 72,6% in our study sample). Our approach of recruiting respondents through email databases of non-vape CBD brands may explain why the sublingual administration route is much more frequent in our study than in the American survey.
The bioavailability of CBD varies by route of administration (Millar et al. 2019), but is generally low, between 10 and 31% (Millar et al. 2018). Oral routes have the lowest bioavailability due to first-pass metabolism, whilst inhaled routes have the highest bioavailability (Ohlsson et al. 1986). The bioavailability of sublingual CBD is between 13 and 19% (Mechoulam et al. 2002), and greater than the oral route, thus exerting effects at much lower doses, making it more efficient for users. Investigating plasma levels of low-dose sublingual CBD users, and correlating them to the subjective experience, might give important insights into the optimal dose for treating these low-level mental health problems like self-perceived stress, anxiety, and sleep problems.
Most people were using less than 100 mg (72.9%) per day. Due to the high price and the lack of medical supervision, it is not surprising that non-medical CBD users are taking much lower doses than those used in clinical studies, and those prescribed for specific medical conditions (Davies and Bhattacharyya 2019; Szaflarski et al. 2018). It is important to highlight that 16.8% reported using more than 100 mg per day, and 10.2% did not know how much CBD they were using. The use of high doses CBD is concerning in light of the current FSA recommendation of restricting the dose to 70 mg CBD per day (Cannabidiol (CBD) n.d.), and it stresses the importance of better public information and communication and improved packaging and guidance from brands to consumers.
Amongst our study sample, almost 11% experienced having a dry mouth, most likely indicating levels of THC in the product, as this is a common side effect of THC rather than CBD (Darling and Arendorf 1993; LaFrance et al. 2020). People living outside of the UK had higher odds of experiencing a dry mouth, which might be explained by the different legislation regarding permitted THC content and CBD quality between countries. This differentiation leads to some concerns about product safety, consistency, and ultimately trust amongst CBD consumers. A recent study of 29 CBD products showed that only 11% contained within 10% of the advertised CBD concentration, 55% of the products had traces of controlled substances such as THC (Liebling et al. 2020). There is still a need for external and internal control within the CBD industry to ensure consumer safety is prioritised.
CBD and self-perceived stress
37.5% of respondents reported using CBD for perceived stress, with 92.2% reporting reduced stress levels, making it the third-highest ranking reason for CBD use amongst our sample. Yet, no studies are looking directly at how CBD affects perceived stress levels. This might in part be because stress, apart from post-traumatic stress disorder, is not classified as a disease according to international disease classification (WHO | Burn-out an “occupational phenomenon”: International Classification of Diseases 2019). With more than 12.8 million working days lost because of work-related stress, anxiety, or depression in the UK (Hse 2019), the relationship between CBD and stress is an area of interest for further research. A recent study surveying social media for comments about perceived therapeutic effects of CBD products revealed that the most frequently discussed symptoms, which are not addressed in the research literature, are indeed stress and nausea (Tran and Kavuluru 2020).
CBD and self-perceived anxiety
Self-perceived anxiety was the top-ranked reason for the use of CBD with 42.6% reporting they take CBD for this reason. Of these, 86.5% reported they felt less anxiety. There are biologically plausible reasons for the use of CBD in anxiety. Pharmacological research suggests CBD is a partial 5-HT1a receptor agonist which supports anxiolytic and stress-reducing properties (Russo et al. 2005; Resstel et al. 2009), the activation of which has been associated with anxiolytic, antidepressant, and antipsychotic effects (Zuardi et al. 1993; Bergamaschi et al. 2011; de Faria et al. 2020; Vilazodone for major depressive disorder | MDedge Psychiatry n.d.; Newman-Tancredi and Kleven 2011). CBD also modulates specifically configured GABAA receptors that may be relevant to anxiolytic effects (Bakas et al. 2017; Deshpande et al. 2011). CBD is anxiolytic under experimental conditions in animals, healthy humans and in those with generalised social anxiety disorder (de Faria et al. 2020; Elms et al. 2019; Newman-Tancredi and Kleven 2011) although large clinical trials have not been conducted. Crippa et al. administered an oral dose of 400 mg CBD or placebo, in a double-blind procedure. They found it significantly lowered feelings of anxiety, accompanying changes in limbic areas, in subjects with social anxiety disorder (SAD) (Crippa et al. 2011). Similar results were seen in a small randomised trial using a public speaking test with 600 mg CBD vs placebo (Bergamaschi et al. 2011).
CBD and self-perceived sleep problems
In our survey, sleep was the second-highest-ranking reason for CBD use. We found that 42.5% used CBD to help with sleep, which is higher than for previously published data on adult CBD users, where it was the fifth-highest reason (Corroon and Phillips 2018). It is well-known that a lack of sleep can cause a variety of physical and mental health effects including raised levels of cortisol(Leproult et al. 1997), anxiety (Babson et al. 2010), and mood disturbances (Brazeau et al. 2010), and both short and long duration of sleep is a significant predictor of death (Cappuccio et al. 2010). A recent controlled study of 300 mg CBD found no effect on any sleep indices (Linares et al. 2018), whilst observational and cross-sectional studies showed improvement in sleep outcomes (Corroon and Phillips 2018; Gulbransen et al. 2020). Preclinical studies have shown mixed results with some doses showing an increase in total sleep time (Chagas et al. 2013) and another study indicating that CBD causes increased wakefulness (Murillo-Rodríguez et al. 2006). Thus, the research on CBD and sleep thus far is mixed. However, as sedation and somnolence are regarded as common adverse effects of CBD in a meta-analysis of clinical trials where high doses are used (Chesney et al. 2020), it may not be surprising that CBD at low doses improved sleep quality and duration.
Given the low quality of CBD available on the market, it may be that these individuals were not taking CBD, or that CBD is not efficacious in sleep, so many individuals report better sleep by virtue of the placebo effect, fuelled by marketing (Haney 2020). Another reason may be that CBD is acting on other aspects of stress and anxiety that indirectly reduce sleep problems. Still, in this survey, participants directly attributed improved sleep to CBD. This points to the need for RCTs, as the effect of expectations (i.e. the result of the placebo effect), particularly with compounds advertised as cure-alls (Haney 2020). Suggesting that the placebo effect may contribute to the purported impact of CBD does not reject the potential medical value of CBD, but it does mean we must be wary of the results of observational studies (Haney 2020).
Strengths and limitations
Our measures were retrospective self-reported symptoms, rather than contemporaneous reports or object assessments, and thus prone to recall bias. This approach may lead to over- or under-estimation of benefits and harms. In reporting anxiety symptoms, it should be noted that many anxiety measures are self-reported, and scales are often an accurate measure of anxiety. Stress itself is not often measured, but scales assessing self-reported stress are reliable (Morgan et al. 2014). Regarding sleep problems, our measures do not accurately correspond with objective measures of sleep such as actigraphy (Girschik et al. 2012), which has implications in the epidemiology of sleep, including in the present study. Future research should use validated measures of anxiety, stress, and sleep. However, it should be noted we included responses to gain an insight where CBD may not help, with about 20% responding that CBD did not help with sleep or anxiety and about 10% saying CBD did not help with stress. There is also a risk of selection biases regarding our recruitment method from email databases of current users and social media recruiting. As we had a self-selected sample, we do not represent the general population or even the overall population of CBD users. It is more likely that respondents with a positive experience have responded to this survey, and continue to use CBD. Still, users with a negative experience may have stopped using CBD and therefore were not reached by this survey, which might further contribute to the selection biases.
The survey demonstrated that CBD is used for a wide range of physical and mental health symptoms and improved general health and wellbeing. A majority of the sample surveyed in this study found that CBD helped their symptoms, and they often used doses below 50 mg. Out of the four most common symptoms, three were related to mental health. Self-perceived stress, anxiety, and sleep problems constitute some of society’s biggest health problems, but we lack adequate treatment options. Further research is needed into whether CBD can efficiently and safely help treat these symptoms.
Availability of data and materials
The datasets used and analysed during the current study are available from the corresponding author on reasonable request.
The reality behind cannabidiol’s medical hype
The cannabis compound known as CBD is being touted as a treatment for a variety of conditions. But the substance’s uncertain legal status is stalling serious investigation.
- Michael Eisenstein0
Michael Eisenstein is a freelance writer in Philadelphia, Pennsylvania.
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Cannabidiol oil has purported health benefits, including helping to relieve chronic pain. Credit: Don Bartletti/Los Angeles Times/Getty
Cannabidiol (CBD) is an illegal drug with no redeeming value. It is also a useful prescription medicine for epilepsy, with considerable potential for treating numerous other conditions. And it is a natural dietary supplement or ‘nutraceutical’ with countless evangelists in the health and wellness community. Although contradictory, all three statements are true from different perspectives, and clinical researchers are frustrated.
“In New York City, you can go to a latte shop and get a CBD product, but if I want to do a clinical trial, I’ve got to get a 2,000-pound safe and go through six months of paperwork and licensing,” says Orrin Devinsky, director of the NYU Langone Comprehensive Epilepsy Center in New York City. Like the cannabis plant from which it is derived, CBD, a type of cannabinoid, is classified by the US Drug Enforcement Administration in the same way as are heroin and lysergic acid diethylamide (LSD) — schedule 1 substances with “high potential for abuse” and “no currently accepted medical use”.
Part of Nature Outlook: Cannabis
This flies in the face of current evidence. Numerous studies have shown that CBD is a safe and non-habit-forming substance that does not produce the ‘high’ associated with tetrahydrocannabinol (THC), the main psychoactive component of cannabis 1 . In 2018, the US Food and Drug Administration (FDA) determined that Epidiolex — a purified CBD product developed by GW Pharmaceuticals in Histon, UK — effectively reduces the frequency of seizures in certain rare forms of paediatric epilepsy. This approval has heartened the cannabinoid research community, which has long recognized the medicinal potential of CBD but come up against scepticism and regulatory constraints on the road to the clinic.
But at the same time, the many manufacturers that promote CBD-laden oils, lotions and foods as a panacea for various health issues, often with minimal regard for local laws or medical evidence, are putting CBD’s medical advocates in an uncomfortable position. “I get calls and e-mails all the time — not just from families, but from physicians who have no clue how to address the requests they get from patients,” says Yasmin Hurd, director of the Addiction Institute of Mount Sinai in New York City. “It’s a real problem.”
Stuck in the weeds
The breakthrough approval of Epidiolex was driven by strong investment from GW Pharmaceuticals, as well as vigorous advocacy from families of children with epilepsy who had heard tantalizing anecdotes about CBD’s effects from jurisdictions in which medical cannabis is legal. “About eight years ago, a patient’s father said he was hearing stories about families in Colorado and California who use high-CBD strains for their kids’ epilepsy,” says Devinsky. “He asked me to do a trial.” As a medical student, he had been taught the history of medicinal cannabis, including well-documented uses of the plant by nineteenth-century physicians to treat seizures. Indeed, cannabis has been part of the clinical armamentarium for epilepsy for more than 4,000 years.
Research on CBD in the 1970s and 1980s focused on its interplay with other cannabinoids, and particularly THC. “Whereas THC can induce psychotic symptoms, impair cognition and make people anxious, CBD appears to do the opposite,” says Philip McGuire, a psychiatrist at King’s College London.
The first clues that CBD might suppress epileptic episodes came from a small clinical trial 2 in 1980. It was led by Raphael Mechoulam, a chemist at the Hebrew University of Jerusalem, whose work on the synthesis and biochemical characterization of cannabinoids in the 1970s had led researchers to begin to explore the medicinal properties of CBD. A number of other trials that explored the compound’s pharmaceutical properties followed, although scientists conducting early forays into CBD clinical research faced an uphill battle. F. Markus Leweke, a psychiatrist who specializes in mental illness at Sydney Medical School, Australia, recalls struggling for seven years to publish findings from a randomized controlled trial that demonstrated that CBD might offer an effective treatment for psychotic symptoms in schizophrenia 3 . “We got about 15 rejection letters,” says Leweke. “And this is a paper that has since been cited almost 500 times.”
Claims about the health benefits of cannabis are often overstated and lack supporting evidence. Credit: Rodger Bosch/AFP/Getty
Forty years on from Mechoulam’s initial work, extensive randomized controlled trials have decisively shown that this purified cannabinoid can profoundly benefit children with certain epileptic disorders. “Over those trials, we saw about a 26–28% reduction in frequency over placebo in all convulsive seizures for Dravet syndrome and drop seizures for Lennox–Gastaut syndrome,” says Devinsky, who has led several such studies 4 , 5 . “Some of the patients became, and remain, seizure-free.”
Preclinical data from rodent and cell-culture studies have hinted at the possible benefits of using CBD to help treat disorders that range from Parkinson’s disease to chronic pain. The range of conditions in which CBD is being tested might seem diverse, but it is a compound with far-reaching, if poorly understood, physiological effects. Antonio Zuardi, a psychiatrist at the University of São Paulo in Brazil, notes that something on the order of 20 possible mechanisms of action have been described to date for CBD. “These multiple pharmacological effects may justify the wide range of possible therapeutic activities.”
The mechanism of CBD’s action on cannabinoid receptors, at least, is well understood. CBD can bind to the cannabinoid receptor CB1, which is the same receptor that THC seeks out in the brain. Unlike THC, however, CBD restrains rather than activates CB1 signalling, and therefore doesn’t induce the psychoactive effects of its cannabinoid cousin.
But CBD wears many hats. It seems to mediate its antiepileptic effects by binding to a protein called GPR55, which can otherwise trigger the onset of seizures by promoting the hyperactivation of neurons 6 . In addition, CBD acts on receptors that mediate pain signalling and inflammation, as well as at least one receptor for the neurotransmitter serotonin, 5-HT1A 7 . Gabriella Gobbi, a psychiatrist and neuroscientist at McGill University in Montreal, Canada, has found that CBD’s physiological effect on the brain resembles that of selective serotonin reuptake inhibitor (SSRI) drugs 8 , which are used to treat clinical depression. “After a few days, you get this desensitization of 5-HT1A, like you would with an SSRI, and increased serotonin signalling,” she says. Further experiments in rats failed to capture an antidepressant effect, but her team found that CBD-mediated modulation of 5-HT1A could relieve neuropathic pain in the animals.
Beyond epilepsy, clinical data to support the medicinal benefits of CBD are more limited, mainly due to the small scale and inconsistent design of trials. “We have very few double-blind, randomized placebo-controlled trials,” says Gobbi. But exciting progress is being made towards treating several conditions.
Psychosis — particularly in the context of schizophrenia — is one such area of promise. In 1995, Zuardi and Mechoulam reported the case of a person with schizophrenia who experienced meaningful relief from their symptoms when treated with high doses of CBD 9 . Several subsequent small-scale clinical studies detected similar hints of efficacy. In their groundbreaking trial 3 , Leweke and his colleagues put the compound through a particularly rigorous test by comparing its effects with those of amisulpride, a potent medication for schizophrenia. “We saw a significant decrease in symptoms over time for both compounds, and CBD beat amisulpride in terms of side effects, by far,” Leweke says. The team also found a clue to the mechanism by which CBD might exert its antipsychotic effects: treatment with CBD was associated with elevated levels of anandamide, a cannabinoid produced by the body that seems to offer protection from psychosis.
McGuire and his colleagues conducted a randomized controlled trial that showed that CBD can have an additive effect when used with conventional antipsychotic drugs 10 . Together, they were better able to control symptoms such as hallucinations and delusions than could conventional medication alone. His team has received funding for a large, international trial to test whether CBD can be developed as a licensed medicine for treating psychosis.
Anxiety disorders are another mental-health condition that CBD has been shown to help alleviate. Zuardi and his colleagues used a test that simulates speaking in public to show that pretreatment with a single dose of CBD can reduce the associated discomfort in people with social anxiety disorder 11 . A similar effect has been observed in healthy people in anxiety-inducing situations 12 , and several researchers are exploring CBD as a means of soothing social stress in people with autism spectrum disorder. Devinsky notes that many of his patients with epilepsy have also been diagnosed with autism spectrum disorder, and he is involved in two clinical trials that aim to test whether CBD can meaningfully reduce the irritability and anxiety of those with autism. “Many parents wanted to keep their children on it even if the seizures didn’t improve, because they’re calmer and sleeping better,” he says.
And although cannabis been demonized as a gateway to more dangerous substances, Hurd has found that it might actually contain an effective antidote for potentially deadly addictions. After observing that rats with a heroin addiction were less likely to seek out the opioid when treated with CBD, she began to investigate whether CBD might have the same effect on people with an opioid dependency. On the basis of an encouraging pilot study, Hurd and her team conducted a randomized controlled trial in 42 abstinent heroin users, who had avoided taking the drug for up to three months after years of routine or heavy use 13 . The researchers then exposed the participants to drug paraphernalia and videos that showed heroin use — cues that normally provoke strong cravings in people with a dependency — and then measured participant-reported responses and physiological indicators of stress and anxiety. “Cue-induced craving is associated with increased cortisol levels and increased heart-rate, and CBD reduced those,” she says. Participants receiving CBD also reported lower levels of drug craving and anxiety relative to placebo group, and Hurd notes that the beneficial effects persisted for a week after the final administration of CBD.
A difficult delivery
Despite its promise, CBD’s impact as a drug has been mixed. Importantly, it is relatively safe. The side effects most commonly associated with a high dose of Epidiolex include digestive problems, rash and drowsiness, as well as the potential for liver damage in patients taking certain other medications. For example, Devinsky notes that patients who are receiving valproic acid to treat seizures or migraines might be at an elevated risk. But in many of the CBD trials conducted so far — particularly in the realm of antipsychotic drugs, which are known for their strong side effects — CBD has proved more tolerable than existing alternatives. “The side effects weren’t significantly worse than with placebo,” says McGuire of his 2018 study of CBD in people with schizophrenia 10 .
This is important because people typically require large doses of the drug to experience a clinical benefit — in many studies, the doses used are as high as 1 gram or more. This is because CBD is poorly absorbed by the body, with most of every dose being excreted before it can take effect. “If you take it orally, the bioavailability is in the range of 4–6%, which is terrible,” says Devinsky. “If you take it after a fatty meal, you can get that up to 16–20%.” Zuardi notes that his group routinely observes a bell-shaped dose–response curve for CBD. For example, whereas 300 milligrams of CBD might reduce a person’s anxiety, the same person might not get any relief from a dose of either 100 milligrams or 900 milligrams. To complicate matters further, this sweet spot for CBD dosing can differ not only between symptoms, but also between patients.
Campaigners show support for legalizing cannabis for medical use in Atlanta, Georgia. Credit: Erik S. Lesser/EPA/Shutterstock
This is one of several reasons why researchers caution against self-medication with CBD products targeted at consumers. CBD is available in shops worldwide, but the legality of such sales varies widely. In Canada, selling cannabis and its derivatives is legal, whereas the European Union authorizes the sale of CBD derived from hemp (low-THC varieties of cannabis) but not from marijuana (high-THC cannabis). In the United States, the latest Farm Bill, which was enacted in 2018, potentially legalizes the production of CBD from hemp under certain conditions — although the sale of CBD products generally remains ostensibly illegal. Regardless of the legal situation at the federal level, CBD commercialization remains something of a free-for-all in the United States — individual states are making their own laws, and the FDA has taken only limited action to enforce federal laws on CBD. “They’ve sent some notices to companies that have made medical claims, but that’s about it,” says Marcel Bonn-Miller, a psychologist at the University of Pennsylvania, Philadelphia, and global scientific director at Canopy Growth Corporation, a cannabis company in Smiths Falls, Canada. (An FDA spokesperson responded that the agency “is working quickly to continue to clarify our regulatory authority over products containing cannabis and cannabis-derived compounds like CBD”.)
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Many such claims lie beyond the bounds of medical evidence — including that regarding CBD preparations that purport to prevent cancer or to treat Alzheimer’s disease. However, even products that make more modest claims could be problematic. In 2017, Bonn-Miller and his colleagues performed chemical analyses on 84 products purchased online from 31 companies, and found that only 31% were accurately labelled with regard to CBD content 14 . What’s more, many commercially available preparations have been found to be contaminated with intoxicating doses of THC, heavy metals and pesticides, as well as toxic solvents from the CBD extraction process. In a case reported by the US Centers for Disease Control and Prevention, up to 52 people in Utah became seriously ill or were hospitalized after using a CBD oil that contained an intoxicating synthetic cannabinoid drug. The possibility of such contamination is concerning to all potential users, and especially to people who are seeking relief from the effects of a health condition. “It’s one thing if you’ve got too much THC in gummy bears you’re using with friends, but something entirely different if it’s a kid you’re giving CBD for medical reasons,” says Bonn-Miller. “I don’t trust any CBD product until I’ve done the tests.”
Between two worlds
The regulatory disconnect that surrounds CBD creates an odd situation in which the public can self-medicate using a potentially questionable product, while scientists face a struggle to perform high-quality clinical trials. “The fact that CBD remains schedule 1 in the United States is unconscionable,” says Devinsky. That restrictive classification, he says, “is impairing research”.
Obtaining sufficient quantities of pharmaceutical-grade CBD to conduct a well-powered clinical trial is already difficult. “It’s extremely expensive,” says Leweke. “You need about one gram a day, and the list price is about 60 euros [US$67] per gram.” This is because the process of extracting CBD from the cannabis plant is complex and arduous — and when the goal is to obtain CBD for use in people, the substance must meet the high bar set for clinical-grade preparations, under which only minimal quantities of THC or other contaminants are permissible. Several companies have developed strategies for manufacturing fully synthetic CBD, an approach that essentially eliminates concerns about purity. But synthetic CBD still falls under the schedule 1 classification in the United States, which creates extra economic and bureaucratic hurdles for clinical trials. Even in Canada, where recreational cannabis has been legalized, Gobbi describes a complex application process and a more than six-month wait to obtain government authorization to conduct a CBD study in people or animals.
Unfortunately, if studies such as these are not done — or not done properly — then consumers will be left to fend for themselves in a poorly monitored marketplace. In that scenario, the signal of true clinical benefit would almost certainly be drowned out by the noise from personal anecdotes and the placebo effect, which could jeopardize the future of a potentially valuable medicine. “Humans are notoriously bad when they think they see patterns,” says Devinsky. “When everyone is convinced that they’re right with no data, I call that religion — and CBD is currently religion for the average person.”
Nature 572, S2-S4 (2019)
This article is part of Nature Outlook: Cannabis, an editorially independent supplement produced with the financial support of third parties. About this content.
Updates & Corrections
Correction 23 July 2020: An earlier version of this Outlook article misquoted Gabriella Gobbi. She said that 5-HT1A is desensitized in response to cannabidiol, not sensitized.
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