People Drink ‘Significantly Less Alcohol’ After Smoking Marijuana, Federally Funded Study Shows

OG article by Kyle Jaeger

November 20, 2025

A federally funded study by Brown University researchers, published in the American Journal of Psychiatry, examined the effects of smoked cannabis on alcohol consumption among 157 heavy users. Participants, reporting at least twice-weekly use of both substances, smoked joints in a controlled bar setting with varying THC concentrations (7.2%, 3.1%, or 0.03% placebo). After smoking, they faced alcohol cues and self-administration tasks. Findings showed that higher THC doses significantly reduced alcohol intake—27% for 7.2% THC and 19% for 3.1%—while delaying drinking onset and lowering urges immediately. No consistent effect on cravings occurred, but cannabis appeared to substitute for alcohol via satiation or receptor downregulation in daily users. The study, the first placebo-controlled trial on acute marijuana effects in heavy users, suggests a substitution model where cannabis reduces alcohol motivation. Funded by NIAAA and NIDA, it notes implications for moderation but cautions against recommending cannabis as an alcohol treatment due to risks like cannabis use disorder. Further research on cannabinoids, including CBD, is recommended to inform clinical guidelines.