A landmark study has tied recreational cannabis legalization to a faster rise in hospital admissions for serious heart conditions across the Western United States.
Researchers published the first-of-its-kind analysis Thursday in BMJ Open, crunching more than 50 million hospital discharge records spanning 2012 to 2018. They focused on 13 Western states where recreational cannabis began rolling out in 2014, years ahead of the rest of the country. By 2018, over 98% of residents in that region lived in or bordered a state with legal cannabis sales.
The team tracked hospitalization rates for acute heart failure, heart attack, atrial fibrillation and flutter, ischemic stroke, venous thromboembolism, and ventricular tachycardia. They established a two-year baseline before legalization took effect, then compared Western trends against regions where recreational cannabis remained illegal.
Before the laws changed, hospital discharge rates for these cardiovascular conditions were actually lower in the West than elsewhere. After enactment, that pattern flipped. Admissions climbed just over 2% faster for atrial fibrillation, nearly 4% faster for heart failure, and just over 3% faster for heart attacks.
The patients showing up in Western hospitals skewed younger and wealthier than their counterparts in non-legalized regions. Their average age was 51, compared with 55 elsewhere. Twenty-six percent lived in higher-income ZIP codes versus 19% in other areas. They were also less likely to identify as white.
Cannabis may stress the cardiovascular system through multiple pathways: elevated heart rate, blood pressure swings, blood clot formation, and chest pain. Legalization has also coincided with broader use, particularly among older adults who already carry higher baseline risk for heart problems.
“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] hospitalizations,” the researchers said.
The study comes as recreational cannabis now sits legal in 24 US states, often framed as a cultural and criminal-justice milestone. Short-term effects of cannabis use have long been documented, including anxiety, impaired memory, and dry mouth. Longer-term use has been tied to lung and blood vessel damage, plus an emerging condition called scromiting that can trigger life-threatening neurological complications.
The research team flagged important limits to their findings. The observational design could not break down trends state by state, separate methods of consumption like smoking versus edibles, or account for illicit use patterns. That means the study cannot prove legalization directly caused the hospitalization increases.
“While an observational study cannot prove causality, our findings point to potential adverse effects of recreation legalisation on population health,” the researchers said.
They added: “Globally, our findings support a cautious approach to legalization laws accompanied by data collection on [cardiovascular] outcomes.”
The analysis covered Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming.