Potency

Potency in retail cannabis typically refers to the mass percentage of Δ9-THC (sometimes "total THC" including THCA decarboxylation equivalent) per dry weight of flower, or per unit mass/volume of concentrate or edible. ElSohly et al. (2016 Biol Psychiatry) documented that average THC content of U.S. confiscated cannabis rose from ~4% in 1995 to ~12%+ by 2014; contemporary flower routinely exceeds 20%. ⚠️ %THC alone is a poor predictor of subjective effect. It does not account for: the entourage effect of minor cannabinoids (CBD, CBG, CBN, THCV) and terpenes (Russo 2011 Br J Pharmacol); individual pharmacokinetic variability; route of administration; tolerance; or set/setting. Freeman et al. (2021 Addiction) showed that higher-potency products are associated with increased risk of dependence and psychiatric harm, particularly in adolescents. NASEM (2017) explicitly cautions against using %THC as a sole proxy for pharmacological effect. Label accuracy is also an issue: Schwabe et al. (2023 PLoS One) found Colorado flower labels over-reported THC by ~15% on average.