A 20-country panel analysis found medical cannabis legalization was associated with an average annual increase of 26 tons in legal cannabis sales, with a negative association with tobacco use and no clear increase in illicit drug use.
Drug policy researchers, public health economists, legalization advocates and critics
26 tons average annual increase in legal cannabis sales post-legalization
What the researchers found
Fixed effects panel regression across 20 countries (14 with legalized medical cannabis, 6 without) found a strong negative association between tobacco use and medical cannabis sales, while cannabis consumption showed a positive association with medical cannabis markets. Amphetamine use was negatively associated with MC sales, suggesting substitution dynamics. Legalization was associated with an average annual increase of 26.06 tons of MC sales, sustained over time. Excluding the US (a market size outlier), the effect was 20.05 tons.
Why it matters
One of the most persistent concerns about cannabis legalization is that it will increase use of other drugs. This multinational analysis finds the opposite for some substances, with tobacco and amphetamine use negatively associated with medical cannabis markets.
The numbers in context
20 countries (14 legalized, 6 not); legalization associated with +26.06 tons annual MC sales; negative association with tobacco and amphetamine use; +20.05 tons excluding US; sustained growth trajectory post-legalization
How the study worked
Panel data from 20 countries analyzed using fixed effects regression and a dynamic Difference-in-Differences (DiD) approach with multiple time periods. Variables included tobacco use, alcohol consumption, amphetamine, cocaine, and cannabis prevalence, and GDP. Event study estimates assessed post-legalization trajectories.
What this study cannot tell us
Ecological study design means population-level associations cannot be interpreted as individual-level causal effects. Country-level data may mask within-country variation. The US is a major outlier in market size, complicating cross-country comparisons. Differences in legalization frameworks, enforcement, and cultural contexts across countries limit comparability.
How to read the evidence
Multi-country panel analysis with robust econometric methods and robustness checks provides moderate confidence, but ecological design and cross-country heterogeneity limit individual-level causal inference.
When this study was published
2025 publication
The bigger picture
The gateway drug hypothesis predicts that cannabis legalization would increase use of harder substances. This cross-national evidence suggests the relationship may work in the opposite direction for some drugs, with medical cannabis potentially substituting for rather than leading to other substance use.
Questions still open
- Does the negative association with tobacco and amphetamine use reflect direct substitution by individual users or broader market dynamics? Would recreational legalization show similar or different patterns?
Common questions
Did medical cannabis legalization increase hard drug use?
Why was the US excluded in the robustness check?
Read the original research
Medical cannabis legalization and the use of illicit drugs, alcohol, and tobacco.
Journal of cannabis research, 7(1), 65
Citation
Al Hallaj, Hana; Barakat, Zahraa. (2025). Medical cannabis legalization and the use of illicit drugs, alcohol, and tobacco.. Journal of cannabis research, 7(1), 65. https://doi.org/10.1186/s42238-025-00324-5