Medical Cannabis Legalization and Global Substance Use Trends

Medical cannabis programs are expanding worldwide, sparking debate about their health, social, and economic impacts.  Most attention has gone to patient care and public safety, but less is known about how legalization affects overall substance use.  A new study¹ in the Journal of Cannabis Research looked at 20 countries between 2000 and 2023, 14 of which legalized medical cannabis during that time.

The study found that legalizing medical cannabis drives steady market growth and changes patterns of tobacco, alcohol, and drug use in different ways.

How the Study Was Conducted

The researchers used two methods.  First, a fixed-effects regression model tracked how cannabis sales were linked to substance use and economic factors in each country.  Second, a difference-in-differences (DiD) model compared countries that legalized medical cannabis with those that didn’t.

Sales were measured in tons.  Other factors studied included smoking rates, alcohol use, recreational cannabis use, amphetamine and cocaine use, and gross domestic product (GDP).

Key Findings on Substance Use and Cannabis Markets

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Here are the main takeaways:

• Tobacco: More smoking meant fewer cannabis sales. Each 1% rise in smoking cut sales by 8.6 tons per year.
• Cannabis: More recreational use meant stronger medical markets. Each 1% rise added about 4 tons in sales.
• Amphetamines: Higher use meant fewer cannabis sales, cutting 10.5 tons per 1% increase.
• Alcohol: Showed little or no link to cannabis sales.
• Legalization: Boosted medical cannabis sales by 26 tons per year on average.

The Growth Trajectory After Legalization

Legalization led to steady growth.  In the first year, sales rose by just over three tons. By year three, sales were up 31 tons, thanks to wider patient access and better supply chains.  At their peak, sales reached 100 tons.

Even without the United States in the data, the trend held firm, averaging about 20 tons of added sales per year.  This shows legalization drives lasting change, not short-term spikes.

Implications for Substance Use

Medical cannabis appears to replace some substances but not others.  The drop in tobacco use suggests people may swap cigarettes for cannabis, which could benefit public health.  The positive link with recreational cannabis shows culture matters—where cannabis is already accepted, medical markets grow faster.

The negative link with amphetamines suggests some people may choose cannabis over stimulants.  Alcohol, however, showed little change, suggesting cannabis legalization doesn’t replace drinking at the national level.

Overall, legalization shifts substance use in different ways depending on the drug.

Limitations and Considerations

Legalization is more than a legal change—it reshapes markets long-term.  Sales grow, innovation follows, and drug-use patterns shift.

The drop in tobacco use is encouraging, but the strong link to recreational cannabis use means policymakers should watch for overuse.  The benefits of legal markets must also be weighed against risks such as cannabis dependence or heavy use.

The study looked at country-level trends, not individual choices.  That means results show national shifts, not personal cause-and-effect.  Cultural values, enforcement, and healthcare systems likely also shaped the results.

Conclusion

Medical cannabis legalization is more than patient access—it transforms markets and shifts substance use.  By reducing tobacco use, boosting cannabis sales, and influencing stimulant use, legalization stands out as a major policy change with lasting effects.

For governments, the message is clear: good cannabis policy means balancing economic growth with public health protections.

Reference

^{1. Al Hallaj, H., & Barakat, Z. (2025). Medical cannabis legalization and the use of illicit drugs, alcohol, and tobacco. Journal of Cannabis Research, 7(65). https://doi.org/10.1186/s42238-025-00324-5}