Fewer than one-third of consumer CBD products contained an amount of cannabidiol within 10% of what was listed on their labels, according to a new review published in Phytochemistry Letters.
Researchers from L-Università ta’ Malta reviewed 28 peer-reviewed analytical studies published between 2017 and 2025, covering CBD oils, tinctures, edibles, vape products and topicals sold across multiple countries.
Among the 937 products evaluated using a label-accuracy threshold of plus or minus 10%, just 294, or 31.3%, contained CBD levels within the accepted range.
Accuracy varied considerably by product type. Oils and tinctures performed the best, although only 41.3% of the 300 products tested were accurately labeled. Edibles followed at 40.5%, while 24.3% of vape products and just 13.8% of topical products met the accuracy threshold.
Some products contained substantially more or less CBD than advertised, while others marketed as containing CBD had no detectable CBD at all. Researchers also found inconsistencies between individual products from the same package, particularly among gummies, suggesting problems with manufacturing and mixing practices.
The reviewed studies also detected undeclared THC, synthetic and semi-synthetic cannabinoids, heavy metals, pesticides and residual solvents. Some contaminants were found at levels exceeding legal or toxicological limits.
One vape product contained approximately 45% THC, while others contained undisclosed synthetic cannabinoids. Testing of edible products identified contaminants including lead, mercury, arsenic, cadmium and phthalates. THC was also detected in certain products marketed as THC-free.
Researchers said the findings could have implications for dosing reliability and consumer safety, particularly for people taking prescription medications that may interact with CBD.
The review’s authors cautioned that comparisons between studies were limited by differences in testing methods, sampling practices and definitions of label accuracy. However, they said the geographically widespread findings indicate that mislabeling and contamination are systemic issues rather than isolated failures.
Researchers called for standardized testing methods, mandatory contaminant screening, clearer labeling requirements and stronger post-market oversight of consumer CBD products.
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