As was the case in other countries, over-the-counter CBD products in the UK have proved to be substandard. A recent analysis of 29 CBD products available to British consumers found that only 38% of the analyzed products were within 10% of the advertised CBD content. The finding is concerning, having in mind that the effects of CBD are dose-dependent, so many consumers could end up failing to achieve the desired effects, and consequentially, develop a misconception that CBD does not work for their condition.

The analysis published in April in Cannabis and Cannabinoid Research shows that only 11 out of 29 of the most popular CBD products available online and on the high street are within 10% of the advertised CBD content. In percentage, that is 38%. The samples from 27 different suppliers also showed measurable levels of controlled substances THC and CBN. As for the range of solvents and heavy metals, many contained detectable levels of N-pentane, ethanol, isopropanol, heptane, lead, and arsenic, but within acceptable levels.

The mean advertised CBD content was 4.5%, and the actual mean measured CBD content of product was 3.2%. Furthermore, 10 out of 29 (34%) products had less than 50% of the advertised CBD content, and one product had 0% CBD.

CBD in the UK: THC and CBN found

Looking into the presence of other cannabinoids, ten percent of the total cannabinoid content of products was other non-CBD phytocannabinoids, including THC, tetrahydrocannabinolic acid (THCA), tetrahydrocannabivarin (THCV), cannabinol (CBN), cannabigerol (CBG), cannabigerolic acid (CBGA) and cannabichromene (CBC). Of these, the highest levels measured were of CBG (mean content 0.05%) and CBC (mean content 0.04%). Fifty-five percent of products had measurable levels of THC (mean content of those with measurable levels is 0.07%) or CBN (mean content of those with measurable levels is 0.04%) and are thus technically illegal to be possessed within the United Kingdom, which has zero tolerance for any controlled substances within CBD. The range of THC content was 0%–0.22%, and the range of CBN content was 0%–0.12%.

Comparison to other countries

The studies that looked at the same issue in other countries have found similar results. In the US, a study testing 84 CBD products found that only 31% 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%. The study was conducted on CBD products sold online and found that the most frequently mislabeled products are vaporization liquids. In the Netherlands, only 5 of 46 products were within 10% of the advertised CBD content, with the percent deviation ranging from 0% to 92%. In Italy, out of 14 CBD oils tested, only five were within 10% of the CBD labeled content, and 12 contained THC, although mostly below 0.2%. CBN was also detected in most samples, which is relevant for the UK, where CBN is still a schedule 1 substance. In Switzerland, the Swiss Association of Cantonal Chemists published the results of their 2021 analysis of the controlled food that contains cannabis or cannabis extracts marketed as CBD. Their results show that 85 out of 100 analyzed products don’t fully meet the safety criteria, with CBD oils worse affected.

In the US, where vape products were found the worst for mislabeling, a study that looked at nine different CBD e-liquid products from a single manufacturer found that two of the products had THC, four contained a potent CB1 receptor agonist called 5-fluoro MDMB-PINACA (5F-ADB), and one contained dextromethorphan from the morphinan class of medications. In the federal state of Utah, between 2017 and 2018, there were 52 cases of people who reported side effects in products labeled as CBD (73% of these were vape products) that were not consistent with CBD consumption, including seizures and vomiting, confusion, and hallucinations. 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 CBD for medical reasons, which is especially worrying for vulnerable populations, as the authors of the recent study point out.

20% of brands don’t carry out purity testing

According to the results of the analysis of CBD in the UK, although present, the contaminants do not pose a threat to British public health. However, a new report from Leafreport, a leading global online reviewer of CBD products, shows concerning figures when it comes to the state of awareness of the importance of the testing on contaminants in this industry globally. The company reviewed 4,384 products from 188 CBD brands and found that only 12% of the brands had all their products fall within acceptable potency variance levels. The results show that 28% of all brands didn’t test for pesticides, 26% didn’t test for heavy metals and 24% didn’t test their products for microbes. An alarming 20% of brands carried out no purity testing on their products at all. In comparison with 2021, transparency within the CBD industry appears to be stagnating and deteriorating in several critical respects, they conclude.

Another recent Leafreport analysis found that looking into CBD sleep products, out of 52 tested products, 60% contained the wrong amounts of CBD, CBN, or melatonin. Over half of the products containing CBD had inaccurate CBD levels. The capsules performed the best out of any product category, with 50% matching the label, followed by 40% of gummies, and 30% of tinctures. The company called the results shocking, illustrating the need for a more transparent CBD industry.

Reviewed by Sasha Bajilo, founder of ILESOL Pharmaceuticals, an industrial scale producer of CBD products and formulations. Expert on Hemp/Cannabis policy, member of the Croatian Ministry of Health regulatory commission for medical cannabis.