Opening Cannabis Stores in Ontario Did Not Increase ER Visits
A natural experiment using Ontario's lottery-based cannabis retailer licensing found no significant increase in emergency department visits for cannabis, alcohol, or opioids after stores opened.
Quick Facts
What This Study Found
The allocation of recreational cannabis retailers through Ontario's randomized lottery system had no significant effect on cannabis-, alcohol-, or opioid-related emergency department visits. Sensitivity analyses using alternate diagnostic codes, co-use patterns, and cannabis-only use all confirmed the null findings.
Key Numbers
11,156,100 adults monitored across 278 communities from January 2016 to March 2023. No significant effects on cannabis-, alcohol-, or opioid-related ED visits after retailer allocation.
How They Did This
Longitudinal study of 278 Ontario communities using health administrative data for over 11 million adults, tracked quarterly from 2016 to 2023. Ontario's lottery-based retailer licensing provided a natural experiment. Researchers used staggered difference-in-differences models weighted by inverse probability of retailer allocation.
Why This Research Matters
A common concern about cannabis legalization is that physical retail access will increase emergency visits. This study leveraged a randomized natural experiment, providing stronger causal evidence than typical observational studies.
The Bigger Picture
The null finding suggests that physical retail access may not be the primary driver of cannabis-related health harms. Online sales, which preceded retail openings, and geographic distribution may have minimized the impact of individual store locations.
What This Study Doesn't Tell Us
Ontario-specific results may not generalize to other jurisdictions. Online cannabis sales were available before retail stores opened, potentially diluting the retail-specific effect. Possible spillover effects between communities with and without retailers.
Questions This Raises
- ?Would results differ in jurisdictions without pre-existing online sales?
- ?Does retailer density matter more than simple presence?
- ?Are there subpopulations where retail access does increase ED visits?
Trust & Context
- Key Stat:
- No significant increase in ED visits after cannabis stores opened
- Evidence Grade:
- Strong: large population-based study leveraging a randomized natural experiment with over 11 million adults tracked over 7 years
- Study Age:
- Published in 2025 using 2016-2023 Ontario health data
- Original Title:
- The impact of recreational cannabis retailer allocation on emergency department visits: A natural experiment utilizing lottery design.
- Published In:
- The International journal on drug policy, 137, 104708 (2025)
- Authors:
- Bai, Yihong(3), Cao, Peiya(3), Kim, Chungah(3), Ienciu, Kristine, Chum, Antony
- Database ID:
- RTHC-05999
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Why is this study design particularly strong?
Ontario distributed cannabis retailer licenses by lottery, essentially randomizing which communities got stores first. This natural experiment design provides stronger causal evidence than typical before-after studies because it controls for many confounding factors.
Why might stores not have increased ER visits?
The researchers suggest several explanations: online cannabis sales were already available, geographic distribution minimized access disparities, and possible spillover effects meant people in communities without stores could still access nearby ones.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-05999APA
Bai, Yihong; Cao, Peiya; Kim, Chungah; Ienciu, Kristine; Chum, Antony. (2025). The impact of recreational cannabis retailer allocation on emergency department visits: A natural experiment utilizing lottery design.. The International journal on drug policy, 137, 104708. https://doi.org/10.1016/j.drugpo.2025.104708
MLA
Bai, Yihong, et al. "The impact of recreational cannabis retailer allocation on emergency department visits: A natural experiment utilizing lottery design.." The International journal on drug policy, 2025. https://doi.org/10.1016/j.drugpo.2025.104708
RethinkTHC
RethinkTHC Research Database. "The impact of recreational cannabis retailer allocation on e..." RTHC-05999. Retrieved from https://rethinkthc.com/research/bai-2025-the-impact-of-recreational
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.