A review published in Phytochemistry Letters found that a majority of consumer CBD products tested in peer-reviewed studies failed to meet common label-accuracy standards, with some products also containing THC, synthetic cannabinoids, heavy metals, pesticides or residual solvents.

Researchers from L-Università ta’ Malta reviewed 28 peer-reviewed analytical studies published between 2017 and 2025, covering 937 consumer CBD products across multiple categories, including oils, tinctures, edibles, vape products and topicals.

The review found that just 31.3% of products, or 294 of 937, met the commonly used ±10% threshold for label accuracy. Oils and tinctures were the most likely to be accurately labeled, with 41.3% of products meeting the threshold. Edibles followed closely at 40.5%.

Vape products and topicals performed considerably worse. According to the review, 24.3% of vape products and just 13.8% of topicals met the ±10% label-accuracy standard.

Researchers said the findings point to “persistent and substantial label inaccuracy” across major CBD product categories. Some products contained significantly less or more CBD than listed on the label, while others had no detectable CBD despite making label claims.

The review also found reports of Δ⁹-THC, synthetic and semi-synthetic cannabinoids, heavy metals, pesticides and residual solvents in consumer CBD products, in some cases at levels exceeding legal or toxicological thresholds.

The authors said the results show ongoing quality-control problems in the consumer CBD market, particularly because many products are sold as foods, supplements, cosmetics or inhalable products outside the stricter regulatory frameworks applied to authorized medicines.

“Evidence indicates quality-control deficiencies across the CBD consumer market, with important implications for consumer safety, dosing reliability, and regulatory oversight,” the study states.

Researchers noted that comparisons across studies were limited by differences in testing methods, product sampling, reporting practices and label-accuracy criteria. However, they said the findings across multiple countries and product types support the need for stronger oversight.

The review concludes that harmonized analytical standards, mandatory contaminant screening, matrix-specific acceptance criteria and strengthened post-market surveillance are needed to better protect consumers.