Does Cannabis Reduce Alcohol Consumption? A New Study Weighs in

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A new clinical trial published in the American Journal of Psychiatry found that cannabis use may reduce how much alcohol people drink in the short term, challenging long-held assumptions about how the two substances interact.

In the randomized, double-blind study, researchers found that participants consumed significantly less alcohol after smoking cannabis containing THC compared to a placebo. The reduction ranged from 19% to 27%, depending on the dose.

The study included 157 participants who reported heavy drinking and regular cannabis use. Across multiple sessions, participants were given cannabis with either 3.1% THC, 7.2% THC, or a near-zero THC placebo, followed by exposure to alcohol cues and a monitored drinking session.

Despite concerns that cannabis might increase alcohol cravings, researchers found no significant change in overall craving scores. However, higher-dose THC did reduce immediate “urge” to drink after use.

The most notable finding was behavioral: Participants drank less alcohol after consuming cannabis. Those given 7.2% THC delayed their first drink and consumed less overall compared to the placebo group.

The findings add new data to a long-running debate about whether cannabis and alcohol act as complements or substitutes. Observational studies have shown mixed results, with some linking cannabis use to heavier drinking and others suggesting it may replace alcohol in certain situations.

Researchers said the results support a “substitution effect,” where cannabis may reduce alcohol intake under controlled conditions. However, they cautioned that participants still drank alcohol after using cannabis, and the study does not support using cannabis as a treatment.

The trial focused on frequent cannabis users, many of whom met criteria for cannabis use disorder. Researchers noted that results may differ for occasional users or those with more severe alcohol dependence.

The study also comes as cannabis legalization expands and more consumers explore alternatives to alcohol, including THC beverages and “Cali sober” lifestyles that replace drinking with cannabis use.

Despite the findings, researchers warned that more work is needed before drawing firm conclusions about long-term effects or health outcomes.