Colorado Cannabis News

Measuring the accuracy of cannabis labelling in Colorado

Written by Sarah Clark on July 2, 2025. Posted in Cannabis News, Products, Research.

A new study found that cannabis concentrate products in the Colorado market were much more likely to be accurately labelled compared to cannabis flower products.

The study—the first to evaluate the accuracy of THC potency labelling in high-potency cannabis concentrate products, and the largest sample to date examining THC potency labelling in cannabis flower—used samples of products from recreational cannabis stores across Colorado.

Nearly all (96%) of the tested cannabis concentrate products were found to have accurately labelled THC potency based on the state’s ± 15% accuracy threshold. Just over half (56.7%) of dried cannabis flower products were considered accurately labelled.

Secondary testing also found both product types to have slightly less THC content compared to the labelled values.

Researchers tested 281 cannabis products for the study, including 182 flower and 99 concentrate products, which were purchased between November 29th, 2022, and October 3rd, 2023.

These products were purchased from 52 non-medical cannabis stores located in 19 different counties of Colorado. Flower products included both loose flower and pre-rolls. There were also 27 unique forms of concentrate tested. Four purchased flower products were excluded from analysis due to misprinted or absent THC potency labelling.

While the mean labelled THC potency for cannabis flower products was 22.5% for flower and 73% for concentrate products, the mean observed THC potency for flower was 20.8% and 70.7% for cannabis concentrate products.

Of the 178 flower products, 101 (56.7%) were accurately labelled, 54 were over-labelled (30.3%), and another 23 were under-labelled (12.9%).

Of the 99 concentrate products, 95 (96%) were accurately labelled, 2 (2%) were over-labelled, and 2 (2%) were under-labelled

Researchers in the study also observed that the minor cannabinoid, CBG, was more abundant than CBD in both flower and concentrate products.

This study was a collaboration between MedPharm Research LLC, a licensed cannabis testing facility, and a research team at the University of Colorado Boulder.

The report notes that these findings are consistent with over-labelling of THC potency that has also been observed in oral cannabis oil products in Ontario, Canada, as well as in medical edible products purchased from San Francisco, California, Los Angeles, California, and Seattle, Washington. Other similar studies have highlighted this issue with cannabis products in Canada’s illicit and licit markets.