A systematic review of the label accuracy of cannabinoid-based products in regulated markets: is what's on the label what's in the product?

To review the literature regarding label accuracy and contamination of medical cannabinoid-based products. A systematic review with meta-analysis following PRISMA guidelines. This study is registered with PROSPERO (CRD42019131565). Five studies reported label accuracy data ranging between 17% and 86%. Four studies reported contaminants, including pesticides, solvents and AB-FUBINACA. Meta-analysis was limited to the proportion of pesticide-contaminated samples found in two studies (0.25 (95% CI [0.10, 0.40])) and displayed significant heterogeneity. Label inaccuracies and contaminants are found across a spectrum of cannabinoid-based products. The review highlights the paucity and heterogeneity of research relating to cannabinoid-based products in light of changing global legislation. Further robust research is required to support ongoing pharmacovigilance and patient safety.