People with Alcohol Use Disorder often also use cannabis. This is called co-use or polysubstance use. Studies show that individuals with AUD are significantly more likely to use cannabis than the general population.

Sources:

• Yurasek AM, Aston ER, Metrik J. "Co-use of Alcohol and Cannabis: A Review." Current Addiction Reports (2017). https://pmc.ncbi.nlm.nih.gov/articles/PMC7363401/

• Haberstick BC et al. "Prevalence and Correlates of Alcohol and Cannabis Use Disorders." https://pmc.ncbi.nlm.nih.gov/articles/PMC3963405/

2. Three main ways they may interact

a) Substitution (using cannabis instead of alcohol)

Some people reduce alcohol consumption by using cannabis instead.

• This can sometimes lower alcohol intake and related harms.

• However, it may lead to Cannabis Use Disorder if cannabis use becomes problematic.

Sources:

• Lucas P, et al. "Reductions in Alcohol Use Following Medical Cannabis Initiation." https://www.sciencedirect.com/science/article/abs/pii/S0955395920303017

• Recovery Research Institute: "Can cannabis substitute for alcohol?" https://www.recoveryanswers.org/research-post/can-cannabis-substitute-alcohol-people-receiving-treatment-reduce-drinking/

• National Center for Complementary and Integrative Health (NCCIH): https://www.nccih.nih.gov/health/cannabis-marijuana-and-cannabinoids-what-you-need-to-know

• CDC Cannabis Information: https://www.cdc.gov/cannabis/about/index.html

b) Complementary use (using both together)

Others use cannabis alongside alcohol.

• This can increase intoxication and impair judgment more than either substance alone.

• It is associated with higher risks of accidents, impaired driving, risky behaviors, and alcohol-related consequences.

Sources:

• Yurasek AM, Aston ER, Metrik J. https://pmc.ncbi.nlm.nih.gov/articles/PMC7363401/

• Hasin DS, et al. "Cannabis Use, Cannabis Use Disorder, and Comorbid Psychiatric Illness." https://pmc.ncbi.nlm.nih.gov/articles/PMC7793504/

• Cannabis Evidence Project: https://www.cannabisevidence.org/clinician-resources/clinician-briefs/cannabis-and-alcohol-use/

• Psychological Science: "Combining Cannabis and Alcohol Amplifies Crash Risks." https://www.psychologicalscience.org/news/motr/combining-cannabis-and-alcohol-amplifies-crash-risks.html

c) Cross-sensitization

Both substances affect the brain’s reward system, including dopamine pathways.

• Using one substance may increase craving or sensitivity to the other.

• This may make quitting either substance more difficult.

Sources:

• Yurasek AM, Aston ER, Metrik J. https://pmc.ncbi.nlm.nih.gov/articles/PMC7363401/

• Metrik J, et al. "Acute Effects of Cannabis on Alcohol Craving and Consumption." American Journal of Psychiatry (2026). https://psychiatryonline.org/doi/10.1176/appi.ajp.20250115

• Columbia University Medical Center: https://www.cuimc.columbia.edu/news/latest-research-shows-marijuana-use-may-be-gateway-relapse

3. Effects on the brain and behavior

Alcohol and cannabis affect overlapping neurological systems.

• Alcohol: depresses the central nervous system, impairing coordination, reaction time, and decision-making.

• Cannabis affects memory, attention, perception, and motivation.

Together, they can:

• Worsen cognitive impairment.

• Increase risk of dependency and substance use disorders.

• Heighten anxiety, depression, or other psychiatric symptoms in some individuals.

Sources:

• NIAAA: https://www.niaaa.nih.gov/

• CDC Cannabis Information: https://www.cdc.gov/cannabis/about/index.html

• NCCIH Cannabis Information: https://www.nccih.nih.gov/health/cannabis-marijuana-and-cannabinoids-what-you-need-to-know

• Yurasek AM, Aston ER, Metrik J. https://pmc.ncbi.nlm.nih.gov/articles/PMC7363401/

4. Mental health connections

Co-use is linked with:

• Higher rates of anxiety and depression.

• Greater severity of substance use disorders.

• More difficulty achieving positive treatment outcomes.

Sources:

• Hasin DS, et al. https://pmc.ncbi.nlm.nih.gov/articles/PMC7793504/

• Kelly TM, Daley DC. "Integrated Treatment of Substance Use and Psychiatric Disorders." https://pmc.ncbi.nlm.nih.gov/articles/PMC3753025/

• Subbaraman MS et al. "Cannabis Use During Treatment for Alcohol Use Disorders Predicts Alcohol Treatment Outcomes." https://pubmed.ncbi.nlm.nih.gov/27865015/

5. Treatment implications

For people with AUD:

• Cannabis use can help, hinder, or complicate recovery depending on the frequency and pattern of use.

• Research suggests cannabis use during alcohol treatment may be associated with poorer alcohol-abstinence outcomes in some individuals.

• Integrated treatment approaches that address multiple substance-use issues simultaneously generally produce better outcomes than treating them separately.

Sources:

• Subbaraman MS, et al. https://pubmed.ncbi.nlm.nih.gov/27865015/

• Subbaraman MS, et al. https://pmc.ncbi.nlm.nih.gov/articles/PMC11347081/

• Kelly TM, Daley DC. https://pmc.ncbi.nlm.nih.gov/articles/PMC3753025/

Bottom Line

There is no one-size-fits-all answer:

• Cannabis may reduce alcohol use for some individuals.

• For others, it may increase risk and worsen treatment outcomes.

• Overall, regular combined use of alcohol and cannabis is associated with greater impairment, more alcohol-related consequences, increased risk-taking, and more complex recovery challenges than using either substance alone.

Key References

1.      Co-Use of Alcohol and Cannabis: A Review https://pmc.ncbi.nlm.nih.gov/articles/PMC7363401/

2.      Cannabis Use During Treatment for Alcohol Use Disorders Predicts Alcohol Treatment Outcomes https://pubmed.ncbi.nlm.nih.gov/27865015/

3.      Cannabis Use, Cannabis Use Disorder, and Comorbid Psychiatric Illness https://pmc.ncbi.nlm.nih.gov/articles/PMC7793504/

4.      CDC Cannabis and Public Health https://www.cdc.gov/cannabis/about/index.html

5.      National Institute on Alcohol Abuse and Alcoholism (NIAAA) https://www.niaaa.nih.gov/

6.      Integrated Treatment of Substance Use and Psychiatric Disorders https://pmc.ncbi.nlm.nih.gov/articles/PMC3753025/