Accuracy of labeled THC potency across flower and concentrate cannabis products.

High total tetrahydrocannabinol (THC) cannabis products are quickly gaining market share across the U.S., but it is unknown whether labeled cannabinoid content accurately reflects true product potency. This study aimed to assess discrepancies between labeled and observed THC content in flower and concentrate products. A representative sample of 277 cannabis flower (n = 178) and concentrate (n = 99) products were purchased from 52 Colorado dispensaries and analyzed for THC content. Products were classified as accurately labeled if observed THC was within ± 15% of labeled THC, and comparative analysis tested observed versus labeled THC content. Labeling accuracy for THC content depended on product type (X(2, n = 277) = 47.44, p < 0.001), with 96.0% of concentrate products being within ± 15% of labeled THC content compared to 56.7% of flower products. Observed THC potency was significantly lower than labeled potency in both flower (U = 18,971, p = 0.001) and concentrate (U = 6095, p = 0.003) products. Nearly all tested concentrate products met the accuracy threshold for THC content, whereas flower products frequently did not. Both product types had lower observed THC content compared to labeled values. Independent and blinded verification of product labels and testing procedures is needed to protect consumers and patients and ensure rigorous testing standards that apply across various types of cannabis products.