Recreational Cannabis Users Drink More on Days They Also Use Cannabis
In daily-level data from Washington State, recreational cannabis users showed a complementary pattern (more drinking on cannabis days), while medical cannabis users showed a substitution pattern (less drinking on cannabis days).
Quick Facts
What This Study Found
At the daily level, recreational cannabis users drank 37% more alcohol on cannabis-use days (IRR = 1.37). Medical cannabis users showed the opposite — a 43% reduction (IRR = 0.57 interaction), suggesting substitution. This indicates the relationship between cannabis and alcohol depends on the type of cannabis user.
Key Numbers
259 respondents, 440 person-waves, 3,051 daily observations. Recreational users: IRR = 1.37 (95% CI: 1.05-1.79) on cannabis days. Medical recommendation interaction: IRR = 0.57 (95% CI: 0.34-0.96).
How They Did This
Three-level negative binomial models analyzing daily alcohol and cannabis use data from 259 co-users across 4 waves of the Washington Panel Survey (2014-2016), with 3,051 daily observations.
Why This Research Matters
Whether cannabis replaces or adds to alcohol use has major public health implications. This study shows it depends on why people use cannabis — recreational users combine them, while medical users may genuinely substitute.
The Bigger Picture
The substitute-vs-complement debate has been inconclusive because researchers haven't distinguished between recreational and medical users. This daily-level analysis resolves the contradiction — both patterns exist in different populations.
What This Study Doesn't Tell Us
Washington State sample during early legalization may not represent current or other markets. Self-reported daily use. Medical recommendation doesn't necessarily mean using for medical purposes.
Questions This Raises
- ?Would medical cannabis programs reduce alcohol-related harm at the population level?
- ?Could recreational legalization increase alcohol-related problems through complementary use?
Trust & Context
- Key Stat:
- Evidence Grade:
- Innovative within-person daily-level analysis resolving a long-standing research question, though limited by single state and early legalization period.
- Study Age:
- Recent analysis of 2014-2016 daily-level data from Washington, one of the first states to legalize recreational cannabis.
- Original Title:
- Does cannabis substitute or complement alcohol after recreational cannabis legalization in the Washington State? A three-level mixed-effects modeling.
- Published In:
- Addictive behaviors, 162, 108218 (2025)
- Authors:
- Zhu, Yachen, Trangenstein, Pamela J(5), Kerr, William C(6)
- Database ID:
- RTHC-08051
Evidence Hierarchy
Frequently Asked Questions
Does cannabis replace alcohol?
It depends on why you use it. Medical cannabis users showed a substitution pattern (less drinking on cannabis days), while recreational users showed complementary use (more drinking on cannabis days).
Why does user type matter?
Medical users may use cannabis therapeutically as an alternative to alcohol, while recreational users may combine both substances as part of social or pleasure-seeking behavior.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-08051APA
Zhu, Yachen; Trangenstein, Pamela J; Kerr, William C. (2025). Does cannabis substitute or complement alcohol after recreational cannabis legalization in the Washington State? A three-level mixed-effects modeling.. Addictive behaviors, 162, 108218. https://doi.org/10.1016/j.addbeh.2024.108218
MLA
Zhu, Yachen, et al. "Does cannabis substitute or complement alcohol after recreational cannabis legalization in the Washington State? A three-level mixed-effects modeling.." Addictive behaviors, 2025. https://doi.org/10.1016/j.addbeh.2024.108218
RethinkTHC
RethinkTHC Research Database. "Does cannabis substitute or complement alcohol after recreat..." RTHC-08051. Retrieved from https://rethinkthc.com/research/zhu-2025-does-cannabis-substitute-or
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.