Recreational Cannabis Laws Linked to 9-11% Drop in Daily Opioid Use Among People Who Inject Drugs | Research

The takeaway

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.

Harm reduction advocates, drug policy researchers, legislators considering cannabis reform, and public health officials addressing the overdose crisis.

What the researchers 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.

Why it 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 numbers in context

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 the study worked

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.

What this study cannot 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.

How to read the evidence

Large multi-state quasi-experimental design with staggered adoption methodology provides strong causal inference, though reliant on self-reported data from serial cross-sections.

When this study was published

Published 2026; covers 2012-2022, spanning the key legalization period.

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.

Questions still open

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?

Common 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.

Read the original research

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

View on PubMed ↗Publisher’s paper ↗

Citation

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