An Analysis of Over-the-Counter Cannabidiol Products in the United Kingdom, Jonathan Paul Liebling et al., 2020

An Analysis of Over-the-Counter Cannabidiol Products in the United Kingdom

Jonathan Paul Liebling, Nicholas James Clarkson, Blair William Gibbs, Andrew Stephen Yates, and Saoirse Elizabeth O’Sullivan

Cannabis and Cannabinoid Research, 2020, 1-7.

DOI: 10.1089/can.2019.0078



Introduction : Over-the-counter cannabidiol (CBD) products have seen unprecedented recent growth in the United Kingdom. However, analysis of these predominantly unregulated products from other countries tells us that they are often mislabeled or contain unlabeled and potentially dangerous chemicals. Thus, the aim of the present study was to analyze CBD oils available in the United Kingdom. Materials and Methods: Phytocannabinoids, residual solvent, and heavy metals were measured blinded in 29 widely available CBD products by an independent testing facility using high-performance liquid chromatography with diode-array detection for cannabinoids, Headspace-gas chromatography-flame ionization detector and gas chromatography–mass spectrometry for residual solvents, and inductively coupled plasma–mass spectrometry for heavy metals.

Results : The mean advertised CBD content was 4.5%, and the actual mean measured CBD content of products was 3.2% ( p = 0.053, Mann–Whitney test). Only 11/29 (38%) products were within 10% of the advertised CBD content. Fifty five percent of products had measurable levels of the controlled substances D9- tetrahydrocannabinol (mean content 0.04%) or cannabinol (mean content 0.01%), as well as most other phytocannabinoid compounds including cannabidiolic acid (CBDA), cannabidivarin (CBDV), and cannabidivarin acid (CBDVA). Detectable levels of N-pentane, ethanol, isopropanol, heptane, lead, and arsenic were found in many of the CBD products, but these were within acceptable levels.

Conclusions : As demonstrated in other countries, the quality of over-the-counter CBD products in the United Kingdom can be substandard, particularly with regard to CBD content, and often contains levels of controlled substances. We recommend that these products be more strictly regulated for consumer welfare.

Keywords : cannabidiol; over the counter; quality; phytocannabinoid


Cannabidiol (CBD) is one of the major constituents of the Cannabis sativa plant of increasing interest due to its broad range of therapeutic properties coupled with a favorable safety and tolerability profile.1,2 The analgesic, anti-inflammatory, antioxidant, anxiolytic, anticonvulsant, and antitumoral effects of CBD are mediated through multiple molecular targets including cannabinoid binding receptor 1 (CB1), cannabinoid binding receptor 2 (CB2) (both generally thought to be indirect), serotonin receptors, opioid receptors, adenosine receptors, orphan receptors such as G proteincoupled receptor 55 (GPR55), GPR18, GPR3, GPR6, and GPR12, peroxisome proliferating activated receptors, transient receptor potential channels, as well as transporters and enzymes.3–6 Clinically, CBD is being investigated in phase 2 and 3 trials in diverse areas including schizophrenia, drug dependency, tumor reduction, pain conditions, and post-traumatic stress disorder. A pure plant-derived CBD product, Epidiolex, recently became the first Food and Drug Administration (FDA)- and European Medicines Agency (EMEA)-approved CBD medicine, indicated for use in childhood Lennox–Gastaut or Dravet syndrome.

The recent change in UK legislation has not resulted in many prescriptions for cannabis-based medicinal
products (CBMPs) within the National Health Service (NHS). However, the public recognition of the medical value of cannabis, coupled with many high-profile stories of patients receiving significant relief with CBMPs, has created huge patient demand for these products. Because of the inability of patients to access CBMPs through their health care providers, they are increasingly turning to over-the-counter cannabis-based products. Since CBD is not a controlled drug in the United Kingdom under the Misuse of Drugs Act or subsequent regulations, CBD-based products have thus become widely available, primarily in an oil format (often called cannabis or hemp oils), although also in many food and beverage products. To remain legally possessed, these products must not contain the psychoactive and controlled chemicals D9-tetrahydrocannabinol (THC) or cannabinol (CBN).

A recent survey in the United States suggests that 62% of CBD consumers are seeking relief of particular
symptoms or medical conditions, with the remaining using CBD as a general wellness product.7 The main medical reasons people use CBD is for pain relief, as a sleep aid, and to reduce anxiety and depression.7 In the United Kingdom, recent market research conducted by the Centre for Medicinal Cannabis suggests that there are 1.3 million regular CBD users.

Studies from other countries have cast doubt over the quality of over-the-counter CBD products. In the
United States, a study of 84 CBD products found that only 31% of products tested were accurately labeled
for CBD content (within 10% of advertised content), and THC was detected in 18 of the samples with a mean level of 0.45% (i.e., above regulated levels).8 A study in the Netherlands showed that only 5 of 46
products were within 10% of the labeled CBD content, and the percent deviation ranged from 0% to 92%.9 A similar study in Italy showed that of 14 CBD oils tested, only 5 were within 10% of the CBD labeled content.10 Twelve of the 14 CBD products in this study contained THC, although mostly below 0.2%. CBN was also detected in most samples, which is relevant for the United Kingdom, where CBN is still a schedule 1 substance. As CBN is an artifact formed by THC oxidation, these data also suggest that there may have been higher levels of THC present in these products at some point.

Bonn-Miller et al.8 found that CBD vape products were the worst for mislabeling of the 84 CBD products they tested. Another US study looked at nine different CBD e-liquid products from a single manufacturer and found that two of the products had THC and four contained a potent CB1 receptor agonist called 5-fluoro MDMB-PINACA (5F-ADB) and one contained dextromethorphan from the morphinan class of medications. 11 In Utah, between 2017 and 2018, there were 52 cases of people who reported adverse reactions in products labeled as CBD (73% of these were vape products) that were inconsistent with CBD consumption, including seizures, vomiting, confusion, and hallucinations.12 Nine products were found to contain a potent synthetic cannabinoid agonist (4-cyano CUMYL-BUTINACA) but no CBD. Fifteen of the people who experienced these adverse reactions were using for medical reasons, which is especially worrying for vulnerable populations.

Based on the increasing CBD consumption in the United Kingdom, and the knowledge that these unregulated products are at best misleading and at worse, pose a health risk, the aim of the present study was to perform detailed analysis of over-the-counter CBD oil products in the United Kingdom. We chose oil products as this is the most common form of delivery for UK consumers and profiled the full phytocannabinoid content of products, as well as other potential contaminants including heavy metals and residual solvents for a fuller safety profile.