States with medical cannabis dispensaries saw 14% more asthma hospitalizations, and states with recreational cannabis saw 20% more, compared to states without these policies.
Pulmonologists, public health planners, and cannabis policymakers.
20.45% increase in asthma hospitalizations in states with legal recreational cannabis
What the researchers found
States with medical cannabis dispensaries experienced a 14.12% increase in inpatient asthma visits compared to states without. States with recreational cannabis legalization saw a 20.45% increase. These increases were primarily driven by Medicare and privately insured populations. Simple passage of medical cannabis laws or home cultivation allowances did not significantly affect asthma hospitalizations.
Why it matters
While cannabis legalization debates focus on addiction and mental health, this study highlights an underappreciated respiratory consequence that carries substantial healthcare costs.
The numbers in context
Medical cannabis dispensaries: +14.12% asthma hospitalizations (2.14 per 100k; 95% CI: 0.74-3.53; p<0.01). Recreational cannabis: +20.45% increase (3.08 per 100k; 95% CI: 1.47-4.69; p<0.001). Effects larger in Medicare populations. No significant effects from law passage or home cultivation alone.
How the study worked
Difference-in-differences regression analysis using state-level quarterly inpatient visit data from the HCUP Fast Stats database (2005-2017). Compared asthma hospitalizations in 38 states before and after implementation of four types of cannabis laws, with analyses stratified by payer type.
What this study cannot tell us
Ecological study cannot confirm individual-level cannabis use caused asthma hospitalizations. Other state-level changes may confound results. 2005-2017 timeframe precedes widespread vaping. Cannot distinguish between patient cannabis use and secondhand exposure.
How to read the evidence
Strong quasi-experimental design with appropriate controls, but ecological data cannot confirm individual-level causation.
When this study was published
2025 publication with 2005-2017 data.
The bigger picture
The finding that actual cannabis access (dispensaries, retail) drives asthma hospitalizations while law passage alone does not suggests the mechanism is increased cannabis smoke exposure rather than a legal status effect.
Questions still open
- Would promoting non-smoked cannabis products reduce the asthma hospitalization impact?
- How much of the increase is from direct use versus secondhand cannabis smoke exposure?
Read the original research
Impact of medical and recreational cannabis laws on inpatient visits for asthma.
Health services research, 60(3), e14427
Citation
Jayawardhana, Jayani; Fernandez, Jose. (2025). Impact of medical and recreational cannabis laws on inpatient visits for asthma.. Health services research, 60(3), e14427. https://doi.org/10.1111/1475-6773.14427
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