Recreational Cannabis Laws Linked to 9-11% Drop in Daily Opioid Use Among People Who Inject Drugs
In the largest study of its kind, states that legalized recreational cannabis on top of medical cannabis saw a 9-11% decrease in daily opioid misuse among people who inject drugs, with cannabis use increases concentrated among White individuals.
Quick Facts
What This Study Found
Compared to medical-only legalization, adding recreational cannabis legalization was associated with a 9-11% decrease in the probability of daily opioid misuse among PWID (any opioids 95% CI: -14.0 to -4.0; injected opioids 95% CI: -19.0 to -2.0), while daily cannabis use increased mainly among non-Latinx White PWID in states transitioning from no law to medical legalization.
Key Numbers
N=28,069 PWID; 13 states; 4 timepoints (2012-2022); MCL+RCL associated with 9-11% decrease in daily opioid misuse; daily cannabis use increased from 15% to 20% among White PWID transitioning from no law to MCL
How They Did This
Staggered adoption difference-in-differences analysis of serial cross-sectional data (2012, 2015, 2018, 2022) from 28,069 people who inject drugs across 13 US states, examining time-varying cannabis law implementation and self-reported substance use.
Why This Research Matters
People who inject drugs face the highest risk of overdose death, and this large-scale evidence suggests recreational cannabis legalization could meaningfully reduce daily opioid use in this vulnerable population.
The Bigger Picture
In the context of an ongoing overdose crisis, this is some of the strongest evidence yet that cannabis legalization may serve as a harm reduction tool for the highest-risk populations.
What This Study Doesn't Tell Us
Observational design despite quasi-experimental methods; self-reported data from a hard-to-reach population; cannot confirm substitution mechanism; racial differences in cannabis uptake suggest structural barriers; serial cross-sections don't track individuals.
Questions This Raises
- ?What mechanisms drive the opioid reduction — direct substitution, reduced exposure, or broader policy effects?
- ?Why do racial disparities exist in cannabis uptake after legalization?
- ?Would targeted cannabis access programs further reduce opioid harm?
Trust & Context
- Key Stat:
- Evidence Grade:
- Large multi-state quasi-experimental design with staggered adoption methodology provides strong causal inference, though reliant on self-reported data from serial cross-sections.
- Study Age:
- Published 2026; covers 2012-2022, spanning the key legalization period.
- Original Title:
- Cannabis legalization and cannabis and opioid use in a large, multistate sample of people who inject drugs: A staggered adoption difference-in-differences analysis.
- Published In:
- Drug and alcohol dependence, 280, 113040 (2026)
- Authors:
- Haley, Danielle F(6), Beane, Stephanie, Beletsky, Leo, Yarbrough, Courtney R, Linton, Sabriya, Ibragimov, Umedjon, Cooper, Hannah Lf
- Database ID:
- RTHC-08306
Evidence Hierarchy
Frequently Asked Questions
Does cannabis legalization reduce opioid use?
This study of 28,069 people who inject drugs found that states adding recreational cannabis laws saw 9-11% less daily opioid misuse compared to states with only medical cannabis laws, suggesting cannabis may serve as a substitute for opioids.
Does cannabis legalization affect everyone equally?
No — increases in cannabis use after legalization were concentrated among White individuals, suggesting structural racism or other factors create unequal access to legal cannabis markets for people of color.
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Cite This Study
https://rethinkthc.com/research/RTHC-08306APA
Haley, Danielle F; Beane, Stephanie; Beletsky, Leo; Yarbrough, Courtney R; Linton, Sabriya; Ibragimov, Umedjon; Cooper, Hannah Lf. (2026). 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 and alcohol dependence, 280, 113040. https://doi.org/10.1016/j.drugalcdep.2026.113040
MLA
Haley, Danielle F, 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 and alcohol dependence, 2026. https://doi.org/10.1016/j.drugalcdep.2026.113040
RethinkTHC
RethinkTHC Research Database. "Cannabis legalization and cannabis and opioid use in a large..." RTHC-08306. Retrieved from https://rethinkthc.com/research/haley-2026-cannabis-legalization-and-cannabis
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.