Study of 50 Million Hospital Records Links Recreational Cannabis Sales to Faster Rise in Heart Admissions

Hospital admissions for three serious heart conditions climbed faster in the Western United States after recreational cannabis sales began there than in regions without legal sales. That is the finding of a study published Oct. 22, 2026, in BMJ Open.

The research team was led by Samuel Slavin of Boston University. It analyzed 50,042,564 hospital discharge records from the National Inpatient Sample covering 2012 through 2018.

What the numbers show

The researchers compared 13 Western states with the rest of the country. The Western group was Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming.

For each year of legal sales, the study estimated these increases in admission rates relative to regions without legal sales:

• Heart failure: 3.7 percent
• Heart attack: 3.1 percent
• Atrial fibrillation: 2.3 percent

Ischemic stroke, venous thromboembolism (deep-vein blood clots) and ventricular tachycardia also trended upward. Those differences were not statistically significant.

The BMJ Group said admission rates for the studied conditions were lower in the West than elsewhere before legalization. "These rates rose faster after legislation," the group said in a statement.

Why the West

Colorado began recreational sales in January 2014, and Washington also began sales in 2014. By 2018, 98 percent of Western residents lived in or next to a state with legal sales, and about 80 percent lived in a state that allowed them.

The first Eastern state to open recreational sales was Massachusetts, in November 2018. That nearly five-year gap gave the researchers a comparison group that mostly lacked legal retail cannabis during the study window.

As a check, the team looked at admissions with cannabis-related diagnoses. Those rose by roughly 14 percent per year of legal sales in the West. The authors expected that increase.

The patient populations also differed. Hospitalized patients in the West had a median age of 51, against 55 elsewhere. They were also more likely to live in higher-income ZIP codes and less often identified as white.

What the authors say they cannot show

The authors state plainly that "observational studies cannot directly establish causality." Hospital records do not show whether any individual patient used cannabis before being admitted.

Still, they wrote that their findings "suggest that recreational cannabis use may have potentially adverse effects on public health." They called for health systems to keep monitoring cardiovascular risk.

A summary of the study from Psychiatric News Alert lists its limits. The analysis did not break out individual states. The regional comparison simplified how cannabis sales actually spread across the West. And although the authors adjusted for many demographic differences, other factors that affected heart health differently in the two regions between 2014 and 2018 could have been missed.

The biology is also not one-directional. THC raises heart rate and blood pressure and can promote clotting. CBD, another cannabis compound, lowers heart rate and blood pressure. That split is one reason earlier research on cannabis and heart disease has been mixed.

The researchers say legalization has coincided with wider cannabis use among older adults, who already face higher cardiovascular risk. They did not measure use directly. As of June 2025, 24 states permitted recreational use and 41 permitted medical use, according to the authors.

The researchers describe this as the first study to examine recreational legalization and cardiovascular hospitalizations. The project was funded by National Institutes of Health grants to two of the authors, who declared no conflicts of interest.

Federal policy and what comes next

The study's policy conclusions are narrow. The authors say the findings support a cautious approach to legalization laws paired with data collection on cardiovascular outcomes.

They also say the results support the proposed federal move of cannabis from Schedule I to the less restrictive Schedule III. Their reasoning is that the change would open the door to research on its cardiovascular effects.

The data end in 2018. Cannabis products and use patterns since then are outside the study window. The authors suggest future work could include prospective policy experiments to pin down the size and timing of any cardiovascular effect, and whether the form of cannabis changes it.