Marijuana Legalization Tied to Rising Heart Attacks and Heart Failure, 50 Million Hospital Records Show
Admissions rose every year after legal sales began in the West, a BMJ Open analysis of 50 million hospital records finds.
Hospital admissions for heart failure, heart attacks and atrial fibrillation climbed faster in the western United States after marijuana legalization brought legal recreational sales, according to a new study of more than 50 million hospital records published in BMJ Open.
For each year of legal sales, admission rates rose nearly 4 percent for heart failure, just over 3 percent for heart attacks, and just over 2 percent for atrial fibrillation, an abnormal heart rhythm. All three increases held up after the researchers adjusted for other factors.
How the marijuana legalization study worked
The researchers drew on the National Inpatient Sample, a federal hospital database covering states home to about 97 percent of Americans. They analyzed 50,042,564 discharge records from 2012 through 2018.
The West offered a natural test. Legal recreational sales began there in January 2014, nearly five years ahead of the rest of the country. By 2018, more than 98 percent of people in the 13-state Western region lived in or next to a state with legal sales. Elsewhere, legal sales did not arrive until late 2018.
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Before legal sales, the West actually had lower rates of these hospitalizations than other regions. After sales began, its rates climbed faster.
The team also ran a check, Gizmodo reported. Cannabis-related diagnoses rose in the West after legalization, while urinary stones, a condition unlikely to have any link to marijuana, held steady.
What the authors say about marijuana legalization
Lead author Samuel Slavin, a cardiologist at Boston Medical Center, called the rise modest for any one person. But he told Gizmodo that “across millions of people, even small shifts can mean a large number of additional hospital visits.”
The authors wrote that their “findings point to potential adverse effects of recreation legalisation on population health.” They concluded that the results “support a cautious approach to legalisation laws accompanied by data collection” on cardiovascular outcomes.
Marijuana’s heart risks keep adding up
The study joins a growing body of research. A 2025 meta-analysis in the journal Heart pooled 24 studies covering about 200 million people. It linked cannabis use to a 29 percent higher risk of acute coronary syndrome and double the risk of dying from cardiovascular disease.
A 2024 study in the Journal of the American Heart Association analyzed CDC survey data on 434,104 adults. Daily users had 25 percent higher odds of a heart attack and 42 percent higher odds of stroke than nonusers. A separate analysis of more than 100 million people tied marijuana use to a 37 percent higher risk of stroke.
The new paper notes that legalization has been associated with wider use, particularly among older adults who already face higher heart risk. Federal survey data show daily use among Americans 35 to 50 at record highs.
Marijuana is usually debated as a mental health issue. Fifty million hospital records suggest it is a heart issue too.
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