Heavy Drinkers Drank Nearly 30% Less Alcohol After One Change in a Lab Study

Cutting back on alcohol is rarely about willpower alone. It often comes down to what changes cravings in the moment and what helps people make different choices when alcohol is right in front of them. A new controlled lab study tested an approach that many people are already experimenting with, using cannabis instead of drinking, and found a noticeable short-term drop in alcohol consumed after participants used higher-THC cannabis. The results are attention-grabbing, but they also raise a bigger question that matters more than any headline: does replacing one substance with another actually reduce harm, or just shift it?

Trial Finds Higher-THC Cannabis Reduced Short-Term Drinking in Heavy Drinkers

A randomized, controlled lab study explored whether cannabis use can change alcohol craving and short-term drinking in adults who already drink heavily and use cannabis regularly. The researchers enrolled 157 adults ages 21–44 who reported heavy drinking and using cannabis at least twice a week.

Each participant completed three separate two-hour lab sessions. In each session, they received one of three options: smoked cannabis with a higher THC level (7.2%), smoked cannabis with a lower THC level (3.1%), or a placebo. After smoking, participants entered a bar-like setting and were given a choice: drink alcohol or take a cash payment instead.

Craving results were not as straightforward. The study reported an immediate drop in “urge to drink” after cannabis in some measures, but the effect was not consistent across all craving assessments—suggesting cannabis may not affect alcohol motivation the same way for everyone.

Short-Term Lab Results Are Not a Treatment Plan

This research tested a short, controlled scenario, not a real-world plan for cutting back on alcohol long-term. The study looked at one cannabinoid (THC), delivered in one form (smoked cannabis), during a two-hour lab session. That matters because cannabis products vary widely, and effects can differ depending on dose, delivery method, and what else is in the product.

It also focused on a specific group: adults who already used cannabis regularly, often close to daily. That means the findings may not apply to people who use cannabis occasionally, or not at all. The researchers also did not evaluate what happens when alcohol and cannabis are used at the same time, which is common in real life and can increase impairment and risk.

Most importantly, the results do not prove cannabis helps people with alcohol-use disorder recover or stay stable over time. Jane Metrik, Ph.D., the study’s lead author, emphasized this point: “For now, I would not recommend using cannabis to cut down on alcohol use.” She also described the findings as a first step, noting that more long-term research is needed before drawing public health conclusions.

Independent experts echoed the caution. Nicole Short, a clinical psychologist who studies cannabis use disorder, warned that the net effect of swapping alcohol for cannabis is still unknown and that longer-term cannabis use could potentially worsen drinking outcomes for some people.

Bottom line: the study suggests a short-term effect in a lab setting, but it does not justify using cannabis as a do-it-yourself strategy to treat problem drinking, especially given the real risk of cannabis use disorder and the lack of long-term safety data.

How Experts Interpret the “Less Drinking After THC” Finding

Outside experts largely agreed the study is useful because it tests cause and effect in a controlled setting, which is rare in cannabis research.

Nicole Short, a clinical psychologist and assistant professor at the University of Nevada, Las Vegas, called the design a “unique study” because it is difficult to administer cannabis in a lab. She also noted the results line up with the “California sober” trend, where some people use cannabis in an attempt to reduce use of other substances. At the same time, Short stressed that the bigger question is what happens over time. She warned it is still possible that “in the longer term, cannabis use may be harmful for drinking outcomes,” and added: “We also don’t know the net effect of swapping out one substance (such as alcohol) for another (such as cannabis).”

Marcel Bonn-Miller, Ph.D., a cannabis researcher with Ajna BioSciences, pointed to real-world behavior changes that are already underway. He said the findings connect to market trends where alcohol sales have decreased as THC has become more accessible. He also emphasized that many consumers are using THC beverages and other non-inhaled products as alternatives to alcohol, and argued that future clinical trials should test whether those formats change alcohol use over time.

Taken together, the expert read is cautious but practical: this trial strengthens evidence that THC can reduce drinking in the short term for some heavy drinkers who already use cannabis, but it does not answer whether substitution is helpful, harmful, or neutral over months and years.

Practical, Safer Ways to Cut Back on Drinking Without Swapping Substances

For readers trying to drink less, the most reliable approach is to use strategies that reduce both opportunity and craving, without introducing a new dependency risk. The study’s authors were clear that the results do not justify using cannabis as a substitute for alcohol, especially because long-term safety and addiction risk are still uncertain.

These steps are commonly used in evidence-based alcohol reduction plans and are practical for everyday life:

• Track intake for 7 to 14 days. Write down each drink, where it happened, and what prompted it. Patterns usually show up fast.
• Set a concrete limit before the day starts. Examples include a fixed number of drinks, a fixed end time, or alcohol-free days each week.
• Change the “first drink” routine. Many people drink on autopilot after work or at dinner. Replace that first cue with a non-alcohol option, a walk, a shower, a meal, or a quick call to someone supportive.
• Slow down drinking pace. Alternate alcoholic drinks with water or a non-alcohol beverage. Eat before drinking. Avoid keeping alcohol within reach at home.
• Plan for high-risk situations. If certain friends, places, or emotions drive drinking, decide ahead of time what the exit plan is, what to order, or whether to skip the event.
• Use professional support early. Brief counseling, structured therapy for alcohol use, and medically supported options can help, especially if cutting back keeps failing or withdrawal symptoms appear.

For anyone already substituting cannabis for alcohol, the safest move is close self-monitoring and a low threshold for getting help. The lead study author, Jane Metrik, Ph.D., said she “strongly encourages” people to consider evidence-based alcohol treatments rather than self-managing with cannabis alone.

Short-Term Effect, Not a Long-Term Solution

This study suggests THC can reduce short-term drinking in a lab setting among heavy drinkers who already use cannabis regularly. That is an important finding, but it does not prove cannabis is a safe or effective strategy for cutting back on alcohol in real life, especially over months or years. As lead author Jane Metrik, Ph.D., put it: “For now, I would not recommend using cannabis to cut down on alcohol use.”

For people who want to drink less, the smartest next step is to use evidence-based tools and get support early. Start by tracking intake, setting clear limits, and changing the routines that trigger that first drink. If cutting back keeps failing, or drinking is affecting sleep, mood, work, or relationships, it is time to talk with a clinician or a licensed therapist. The goal is not to trade one problem for another, but to lower risk and build habits that hold up outside the lab.

Source:

1. Metrik, J., Aston, E. R., Gunn, R. L., & Kahler, C. W. (2025b). Acute effects of cannabis on alcohol craving and consumption: a randomized controlled crossover trial. American Journal of Psychiatry, appiajp20250115. https://doi.org/10.1176/appi.ajp.20250115