Smoking cannabis reduced alcohol consumption by up to 27% in a controlled trial of heavy drinkers | Research

The takeaway

In a double-blind crossover trial of 157 heavy drinkers who also used cannabis, smoking cannabis reduced subsequent alcohol consumption by 19% (low dose) to 27% (high dose) compared to placebo.

Addiction researchers, harm reduction advocates, alcohol treatment clinicians, cannabis policy analysts

27% reduction in alcohol consumption after high-dose THC vs. placebo

What the researchers found

After overnight cannabis abstinence, smoking cannabis with 3.1% or 7.2% THC led to significantly less alcohol consumption compared to placebo, reducing intake by 19% and 27% respectively. High-dose THC also reduced alcohol urge immediately after smoking, though broader craving measures did not show significant effects.

Why it matters

This is the first controlled human study to establish a causal effect of cannabis on alcohol consumption. Published in the top psychiatry journal, it provides rigorous experimental evidence for a substitution effect that has previously only been observed in survey and epidemiological data.

The numbers in context

157 participants randomized, 138 completed 2+ sessions. Mean age 25.6 years, 35% women, 45% racial/ethnic minorities. 7.2% THC reduced alcohol consumption by 27%. 3.1% THC reduced alcohol consumption by 19%. 7.2% THC reduced alcohol urge immediately after smoking.

How the study worked

Double-blind crossover RCT published in the American Journal of Psychiatry. 157 participants who reported heavy alcohol use and cannabis use at least twice weekly completed three experimental sessions with different THC doses (7.2%, 3.1%, 0.03% placebo). Each session included neutral and personalized alcohol cue exposure followed by an alcohol self-administration task. 138 completed two or more sessions.

What this study cannot tell us

Laboratory setting may not reflect real-world drinking. Participants were regular cannabis users, so results may not apply to cannabis-naive individuals. Short-term effects only; long-term substitution patterns not addressed. The study examined acute effects after overnight abstinence from cannabis.

How to read the evidence

Double-blind, placebo-controlled crossover RCT published in the American Journal of Psychiatry with adequate sample size and rigorous methodology.

When this study was published

2026 publication in the American Journal of Psychiatry

The bigger picture

Alcohol use disorder kills approximately 140,000 Americans annually. If cannabis can reliably reduce alcohol consumption, it could have significant harm-reduction potential, though the tradeoffs of substituting one substance for another remain debated.

Questions still open

Would this substitution effect persist over weeks or months of regular use? Does it work for people who do not already use cannabis? What are the net health effects of substituting cannabis for alcohol?

Common questions

Does this mean cannabis is a treatment for alcoholism?

Not yet. This study shows cannabis can acutely reduce alcohol consumption in a lab setting, but it does not test long-term treatment outcomes or whether the approach is safe and effective as a clinical strategy.

Did cannabis eliminate alcohol cravings?

High-dose THC reduced the immediate urge to drink after smoking, but broader craving questionnaire measures did not show significant differences, suggesting the effect may work more through behavioral substitution than craving reduction.

Read the original research

Acute Effects of Cannabis on Alcohol Craving and Consumption: A Randomized Controlled Crossover Trial.

The American journal of psychiatry, 183(2), 134-143

View on PubMed ↗Publisher’s paper ↗

Citation

Metrik, Jane; Aston, Elizabeth R; Gunn, Rachel L; Swift, Robert; MacKillop, James; Kahler, Christopher W. (2026). Acute Effects of Cannabis on Alcohol Craving and Consumption: A Randomized Controlled Crossover Trial.. The American journal of psychiatry, 183(2), 134-143. https://doi.org/10.1176/appi.ajp.20250115