Subjects voluntarily reduce their alcohol intake following the use of cannabis, according to the results of a clinical trial published in the American Journal of Psychiatry.

Researchers affiliated with Brown University’s School of Public Health assessed whether cannabis use influenced subjects’ desire for alcohol. Study participants had a history of alcohol and cannabis use. Subjects randomly inhaled herbal cannabis containing either 7.2 percent THC, 3.1 percent THC, or 0.3 percent THC (placebo). Researchers then assessed how much alcohol participants consumed over the following hour.

Study participants significantly reduced their alcohol intake following the inhalation of low and moderately potent cannabis, but not after consuming the placebo. Specifically, those participants consuming cannabis containing 3.1 percent THC decreased their alcohol consumption by 19 percent relative to placebo. Those consuming cannabis containing 7.2 percent THC decreased their consumption by 27 percent relative to placebo.

Participants who consumed higher THC flower also reported less of a desire for alcohol and waited longer before consuming their first drink as compared to those who consumed either low-potency cannabis or placebo.

“We found that smoked cannabis with 3.1 percent and 7.2 percent THC doses acutely decreased alcohol consumption and increased latency to drink under controlled laboratory conditions, relative to placebo,” the study’s authors concluded. “The findings suggest that smoked cannabis reduces alcohol consumption and, conversely, acute cannabis deprivation (i.e., in the placebo condition) may lead to compensatory increases in alcohol intake.”

The study’s findings are consistent with those of a paper published in September in the journal Drug and Alcohol Dependence. That study reported that subjects reduced their consumption of alcohol beverages by 25 percent in the hour immediately after they smoked cannabis.

Commenting on the findings, NORML’s Deputy Director Paul Armentano said: “These findings provide support for the idea that legal cannabis can serve as substitute for alcohol among certain individuals, and that legal cannabis markets may, in some instances, disrupt alcohol-dominant marketplaces.”

According to survey data published in 2024 in The Harm Reduction Journal, 60 percent of cannabis consumers say that their cannabis use results in less frequent alcohol consumption.

Data from jurisdictions with regulated cannabis markets typically show declining alcohol sales following legalization. Specifically, a study published this summer in the journal Addiction identified sustained declines in Californians’ weekly drinking patterns, as well as in how often they engaged in heavy episodic drinking, following legalization. In Canada, alcohol sales have similarly declined following the adoption of adult-use marijuana legalization.

The full text of the study, “Acute effects of cannabis on alcohol craving and consumption: A randomized controlled crossover trial,” is available from the American Journal of Psychiatry.