Legalisation of recreational cannabis in the US is associated with a rise in hospital admissions for cardiovascular disease, finds an analysis of more than 50 million patient discharge records, published in the open access journal BMJ Open.
Admissions for atrial fibrillation (abnormal heart rhythm), heart failure, and heart attack all rose faster after the law was enacted in the Western region of the US with the policy than in states without, the analysis shows.
Cannabis use has the potential to affect cardiovascular health through various physiological mechanisms, explain the researchers. And legalisation policies have been associated with more widespread use of cannabis products, particularly among older people who are already at heightened risk of cardiovascular problems, they add.
As of June 2025, medicinal cannabis use was legal in 41 US states, while recreational use was legal in 24, they point out.
To gauge the potential impact of recreational cannabis laws on cardiovascular health, the researchers obtained data on hospital discharge diagnoses and patient demographics from the National Inpatient Sample (NIS) for the years 2012-18 inclusive: NIS participating states cover around 97% of the US population.
The researchers focused on the Western region of the USA (Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming), because it began legalising recreational cannabis in January 2014.
This was nearly 5 years before other regions, so that by 2018, over 98% of people in the Western region lived in, or bordered, a state with legal cannabis sales.
The researchers analysed hospital admission rates for acute heart failure, heart attack, atrial fibrillation/flutter, ischaemic (blood clot) stroke, venous thromboembolism or VTE for short (deep vein blood clot), and ventricular tachycardia (fast heartbeat).
For each of these diagnoses, they estimated baseline regional rates of hospital admissions per 100 000 people, using weighted NIS data for the 2 years before the first legal sale of recreational cannabis.
They looked at these rates before and after legalisation in the Western region and compared these with other regions that hadn't enacted the legislation. In all, they analysed data for 50,042,564 hospital discharge records between 2012 and 2018.
During the study period, people admitted to hospital in the Western region were overall
younger (average age 51 vs 55), lived in higher-income ZIP codes (26% vs 19%) and less often identified as White.
Before the legislation (2012–13), hospital discharge rates for the included diagnoses were lower in the Western region than in regions without the legislation. But these rates rose faster after legislation.
The estimated change in admission rates for each year of legal cannabis sales was statistically significant for atrial fibrillation (just over 2% higher), heart failure (nearly 4% higher), and heart attack (just over 3% higher), after adjusting for potentially influential factors.
Rates for the other studied outcomes were higher, but not statistically significant.
This is an observational study, and as such, can't establish cause and effect, and the researchers acknowledge various limitations to their findings. These include the inability to separate out individual states or look at the method of cannabis use (smoked or not). Nor were they able to account for trends in illegal use.
Nevertheless, they point out: "While several studies have examined the association of recreational cannabis legalisation on psychiatric conditions, substance use, emergency visits, and traffic accidents, ours is the first study to examine the association with [cardiovascular] hospitalisations."
They add: "While an observational study cannot prove causality, our findings point to potential adverse effects of recreation legalisation on population health.
"Globally, our findings support a cautious approach to legalisation laws accompanied by data collection on [cardiovascular] outcomes."
