Cannabis users drink less alcohol: study

Smoking cannabis appears to reduce the consumption of alcohol under some conditions, but it remains unclear whether this would lead to a decrease in harms, reports a study.

“[S]moked cannabis induced acute increases in subjective intoxication, affect, arousal, cardiovascular effects, blood delta-9-tetrahydrocannabinol (THC) concentrations, and acutely reduced alcohol consumption without a consistent effect on alcohol craving,” the investigators said.

“Notably, participants still consumed alcohol after smoking cannabis with THC, although they drank less than when they were not acutely intoxicated with THC,” they added.

A total of 157 individuals reporting heavy alcohol use and cannabis use at least two times weekly participated in this study conducted across three experimental days. Participants were randomized to smoke cannabis cigarettes containing 7.2% THC, 3.1% THC, or 0.03% THC (placebo), followed by exposures to neutral and personalized alcohol cues and choice task for alcohol self-administration.

Of the participants, 138 (mean age 25.6 years, 35 percent women, 45 percent racial/ethnic minorities) completed two or more experimental sessions. The primary outcomes were craving, Alcohol Craving Questionnaire‒Short Form (Revised; ACQ-SF-R), and an alcohol urge question, while the percentage of total available millilitres of alcohol consumed served as the secondary outcome.

Cannabis did not have any significant effects on ACQ-SF-R ratings after smoking and during alcohol cue exposure. However, 7.2% THC was associated with a decrease in alcohol urge immediately after smoking. [Am J Psychiatry 2026;183:134-143]

Furthermore, alcohol consumption decreased among participants after smoking cannabis with 3.1% THC and 7.2% THC, with reductions of 19 percent and 27 percent, respectively.

Effect of THC

These findings support those of a controlled experiment that noted reduced 10-day alcohol consumption when smoked cannabis was concurrently available compared with days when only alcohol was available. [J Pharmacol Exp Ther 1978;207:922-935]

“The present study also extends the results of Venegas and Ray by using a placebo control condition and cannabis with two THC doses administered in the laboratory versus in participants’ homes, showing that THC administration led to a significant reduction in alcohol consumption,” the investigators said. [Exp Clin Psychopharmacol 2023;31:683-693]

“This level of experimental control strengthens causal inference regarding the effect of THC on alcohol consumption,” they added.

Previous experimental studies that combined the administration effects of THC and alcohol observed decreases in peak plasma ethanol levels, increased blood THC levels, and positive subjective effects. However, no study explored how coadministration impacted subsequent alcohol intake. [Drug Alcohol Depend 2001;64:143-149]

Therapeutic potential

“While there is growing recognition of the therapeutic potential of cannabinoids, it would be premature and potentially risky at this time to recommend cannabis as a therapeutic substitute for alcohol or as a harm-reduction strategy for alcohol use disorder,” the investigators said.

For patients who are already using cannabis as alcohol substitute, clinicians are advised to provide guidance on the risks of cannabis use disorder, monitor cannabis use, and continue recommending evidence-based alcohol treatments, they added.

“Long-term substitution patterns and the potential of progression to problematic cannabis use with reduced alcohol use should be examined with high priority in future studies,” the investigators said. “Healthcare providers and cannabis product marketing should be cautious about endorsing substitution without clear evidence of long-term safety and efficacy.”