Is Cannabis a Substitute for Other Substance Use?

With more widespread legalization and use of cannabis in states throughout the US, there have been indications that some individuals may be substituting cannabis for alcohol and non-medical opioid use. Two recent studies investigated this possible link in specific populations.

Haley et al used data from a serial cross-sectional observational study of people with injection drug use to analyze the effect of changes in state cannabis laws (CL)—medical legalization (MCL) or recreational legalization (RCL)—and non-medical opioid use outcomes.

• Between 2012 and 2022, there was a similar increase in the percentage of people reporting daily cannabis use in states that transitioned toward legalization and those that did not.
• In states that transitioned from MCL to MCL+RCL, there was a 9 percent reduction in the probability of daily non-medical opioid use. There was no significant change in states that transitioned from no CL to MCL only.

Whitney et al looked at data from an observational cohort of 12,143 people with HIV to see if changes in cannabis use were associated with changes in alcohol use and combustible cigarette smoking, 2009–2023.

• At baseline, 32 percent of the cohort reported cannabis use, 36 percent smoked cigarettes, and 18 percent reported hazardous alcohol use.*
• Increasing cannabis use was associated with higher frequency of alcohol use and increased odds of hazardous alcohol use.
• Increasing cannabis use was likewise associated with increased cigarette smoking.

* Defined as an AUDIT-C score of ≥5 for men and ≥4 for women.

Comments: Overall, these studies do not support the hypothesis that individuals substitute cannabis for alcohol or non-medical opioid use and that cannabis legalization will promote a transition to a less dangerous substance (cannabis). In fact, the second study raises concerns that it may be associated with an increase in the use of other substances in some populations.

Darius A. Rastegar, MD, MSc

References: Haley DF, Beane S, Beletsky L, et al. Cannabis legalization and cannabis and opioid use in a large, multistate sample of people who inject drugs: a staggered adoption difference-in-differences analysis. Drug Alcohol Depend. 2026;280:113040.

Whitney BM, Delaney JAC, Drumright LN, et al. Brief report: are changes in cannabis use frequency associated with changes in alcohol use and smoking among people with HIV (PWH)—a substitution question. Drug Alcohol Depend. 2025;277:112958.