A new study reports that for some heavy drinkers, using cannabis may be associated with consuming less alcohol. This reduction in drinking appears linked to a decrease in alcohol craving that occurs after cannabis use, a finding that offers a potential mechanism for why some people might substitute one substance for the other. The research was published in the journal Drug and Alcohol Dependence.
The relationship between cannabis and alcohol use is complex, with past research offering conflicting pictures of how the two substances interact. Some studies suggest that using cannabis increases alcohol consumption, a relationship known as complementarity. Other evidence points to a substitution effect, where people use cannabis in place of alcohol, potentially as a form of harm reduction.
This lack of a clear consensus prompted a team of researchers from Colorado State University and the University of Colorado to investigate the dynamic under controlled laboratory conditions. They aimed to directly test how self-administering commercially available cannabis would affect a person’s subsequent desire to drink alcohol.
To explore this question, the study involved 61 adults between the ages of 21 and 60 who regularly engaged in heavy drinking and used cannabis flower at least three times per week. Each participant acted as their own baseline for comparison by attending two separate laboratory sessions. The sessions took place in a mobile laboratory, a specialized vehicle parked outside the participant’s residence. This unique setup allowed researchers to study the effects of legal, commercial cannabis products, which federal regulations prohibit bringing onto university campuses.
In one session, referred to as the “alcohol only” condition, individuals consumed a small alcoholic “priming” drink, calculated to raise their blood alcohol content just enough to initiate a desire to drink more. Over the next hour, they were given the chance to consume up to four additional alcoholic beverages. To provide an alternative choice, participants received one dollar for each drink they declined. Throughout this period, they periodically rated their level of alcohol craving on a standardized scale.
The second session followed an almost identical procedure, with one key difference. Before receiving the priming drink, participants went inside their residence to use their own cannabis flower product at a dose they would typically consume. After using cannabis, they returned to the mobile lab, where researchers took a blood sample before proceeding with the alcohol administration portion of the experiment. The order of these two sessions, one with cannabis and one without, was randomized for different participants to ensure the sequence did not influence the results.
When the researchers analyzed the data, they found a notable pattern in overall alcohol consumption. On average, participants drank approximately 25 percent fewer alcoholic drinks during the session where they first used cannabis compared to the session with alcohol alone. The mean number of drinks consumed dropped from 2.09 in the alcohol-only session to 1.60 in the session that included cannabis.
To understand this average effect better, the team looked at individual behaviors and identified three distinct patterns. One group of 23 participants, termed “substituters,” drank fewer alcoholic beverages after using cannabis. Another group of 23, the “non-substituters,” drank the same number of drinks or more. A third group of 15 participants, called “abstainers,” chose not to consume any of the additional drinks in either of the sessions.
The most informative difference between the groups emerged when the researchers examined self-reported alcohol cravings. The “substituters” reported a significant drop in their urge to drink at several points in time after they had consumed cannabis. In contrast, the craving levels for “non-substituters” remained relatively stable or even slightly increased during the session that combined cannabis and alcohol. This suggests that for individuals who end up drinking less, a cannabis-induced reduction in alcohol craving may be an important contributing factor.
The team also checked if the amount of cannabis consumed could explain these different behaviors. An analysis of blood samples showed no significant difference in the concentration of THC, the main psychoactive component in cannabis, between the substituter and non-substituter groups. This finding indicates that the tendency to substitute cannabis for alcohol was not simply due to consuming a larger or more potent dose of cannabis. Instead, it points toward individual differences in how people respond to the substance.
The authors acknowledged several limitations to their work that suggest areas for future inquiry. The experiment took place in a mobile laboratory, which is not a typical setting for drinking, and this environment may have influenced participants’ behavior. Because individuals used their own cannabis, the dose and potency were not experimentally controlled, a trade-off made to increase the study’s real-world relevance. Cannabis was always administered before alcohol, so the study cannot determine if the order of consumption matters.
Additionally, the study’s population was not broadly diverse, with a majority of participants identifying as White and male, meaning the results may not apply to other demographic groups. Future research could address these points by replicating the study in larger and more varied populations.
Scientists could also examine the effects of different cannabis products, such as edibles or concentrates, and control the dose and chemical composition to better understand dose-response relationships. Combining laboratory experiments with real-world monitoring using technologies like alcohol biosensors could provide a more complete picture of co-use patterns.
The study, “Cannabis administration is associated with reduced alcohol consumption: Evidence from a novel laboratory co-administration paradigm,” was authored by Claire L. Pince, Vanessa T. Stallsmith, Cianna J. Piercey, Katelyn Weldon, Jesse Ruehrmund, Gregory Dooley, L. Cinnamon Bidwell, and Hollis C. Karoly.