To our knowledge, this case series study is the first study of label accuracy of cannabis products in the legal Canadian market. We found discrepancies at multiple levels. One-third of purchased products differed from their online THC and CBD descriptions, and 16.7% had conflicting information on the physical label. Compared with assay levels, amounts for 40.0% of products were outside variability limits for THC and 10.0% for CBD; all but 1 were instances of overlabeling. Among higher-potency products (≥2.5 mg/g THC), nearly half were incorrectly labeled as containing THC amounts that were greater than what was indicated by laboratory testing by more than 15%.

Our findings suggest that inaccurate labeling of cannabis oil products in the legal Canadian market is common, with most discrepancies due to labeling products with greater THC or CBD content than was present. No products contained more THC than labeled at an amount that would be expected to have substantively different psychoactive effects. However, given that many medical consumers obtain products from the nonmedical market,⁶ one implication is inaccurate dosing. Altogether, these findings suggest a need for greater quality control in the Canadian legal cannabis market and undermine the assumption that a legal market is an assurance of accurate labeling. Limitations of our study include a focus on cannabis oils, with uncertain generalizability to other product types, and the sample size of 30 products, which is not representative of all available products in Ontario or Canadian markets.