Five years after recreational cannabis legalization, cannabis use increased by 3.28 percentage points and e-cigarette use by 1.39 points, while cigarette use did not significantly change.
Policymakers, public health officials, and tobacco/cannabis researchers.
Cannabis use rose 3.28 percentage points after legalization, accelerating to 3.74 points after retail outlets opened
What the researchers found
Using difference-in-differences analysis of 171,257 observations from 55,406 individuals, recreational cannabis legalization was associated with a 3.28 percentage point increase in cannabis use and 1.39 percentage point increase in ENDS use compared to control states. Cigarette use did not significantly change (-0.99 points). Cannabis use increased more after retail outlets opened (3.74 points) than before (1.17 points).
Why it matters
This is one of the first studies with enough follow-up to show longer-term effects of cannabis legalization on both cannabis and tobacco product use, using a rigorous causal inference design.
The numbers in context
171,257 observations from 55,406 individuals (50.9% female, mean age 37.97). Cannabis use: +3.28 pp (95% CI: 2.29-4.27). ENDS use: +1.39 pp (95% CI: 0.44-2.35). Cigarettes: -0.99 pp (95% CI: -2.25-0.27, not significant). Post-retail cannabis increase: +3.74 pp vs pre-retail +1.17 pp.
How the study worked
Difference-in-differences analysis of the nationally representative Population Assessment of Tobacco and Health (PATH) longitudinal cohort study (2013-2022), comparing states with recreational cannabis legalization to control states over 5 years.
What this study cannot tell us
Observational design despite difference-in-differences approach. State-level variation in implementation complicates uniform analysis. Self-reported use. Does not capture frequency or quantity changes within users. Cannot identify which individuals are new users versus increased users.
How to read the evidence
Large nationally representative longitudinal cohort with difference-in-differences design provides strong causal evidence. Published in JAMA Network Open.
When this study was published
2025 JAMA Network Open publication with 2013-2022 data.
The bigger picture
The finding that legalization increases cannabis use but not cigarette use addresses a key policy concern. The unexpected increase in e-cigarette use suggests cross-product effects that regulators should monitor, potentially driven by vaping hardware crossover.
Questions still open
- Why did e-cigarette use increase alongside cannabis legalization?
- Does the post-retail acceleration of cannabis use plateau or continue climbing beyond 5 years?
Read the original research
Use of Tobacco and Cannabis Following State-Level Cannabis Legalization.
JAMA network open, 8(7), e2520093
Citation
Hyatt, Andrew S; Overhage, Lindsay; Cook, Benjamin Lê. (2025). Use of Tobacco and Cannabis Following State-Level Cannabis Legalization.. JAMA network open, 8(7), e2520093. https://doi.org/10.1001/jamanetworkopen.2025.20093