Legal marijuana is raising new health concerns after researchers found that hospitalizations for heart attacks, heart failure, and irregular heartbeats increased faster in parts of the United States following recreational cannabis legalization. The findings suggest that expanding access to marijuana could have cardiovascular consequences, although scientists have not established that legalization or marijuana use directly caused the increase.
The study, published in BMJ Open on October 22, 2026, examined 50,042,564 hospital discharge records collected between 2012 and 2018. Researchers compared cardiovascular hospitalization trends in the Western United States, where recreational marijuana sales began in 2014, with other regions that had not introduced legal recreational sales during most of that period.
The researchers found that each additional year of legal cannabis sales was associated with a 3.7% relative increase in heart failure hospitalization rates compared with trends in other regions. Heart attack hospitalizations showed a 3.1% relative increase, while admissions for atrial fibrillation or atrial flutter, conditions involving abnormal heart rhythms, increased by 2.3%.
These percentages represent estimated changes in population hospitalization rates, not an individual marijuana user’s likelihood of developing heart disease. Still, the results introduce another concern about legal marijuana and its potential effects on cardiovascular health, particularly for people who already have heart conditions.
Researchers did not determine whether the people admitted to hospitals had actually used marijuana. Instead, they examined broad changes in hospital records as states changed their cannabis laws. They could not identify which cannabis products patients may have consumed, how often they used them, or how much THC they were exposed to. Other changes unrelated to marijuana could also have influenced regional hospitalization trends. As the study’s authors acknowledged, “an observational study cannot prove causality.”
The analysis also examined ischemic strokes, blood clots in veins, and ventricular tachycardia, a potentially dangerous rapid heartbeat. Those conditions did not show statistically significant increases in the study’s primary adjusted results. Researchers also grouped Western states together, including some where recreational sales had not yet become legal. That approach allowed them to compare regional trends but prevented them from isolating the effects of each state’s marijuana policies.
There are medical reasons scientists are examining legal marijuana and its effects on the heart. THC, the main compound responsible for marijuana’s intoxicating effects, can stimulate the nervous system, increase heart rate, and raise the heart’s demand for oxygen. According to the Centers for Disease Control and Prevention, cannabis can also raise blood pressure immediately after use. Those effects could be especially concerning for people with existing cardiovascular conditions.
How marijuana is consumed may also influence its health effects. Smoking cannabis exposes the body to some of the same harmful substances found in tobacco smoke. Edibles avoid inhaled smoke, but they still deliver cannabinoids, including THC, and have not been established as harmless to cardiovascular health. The new study did not distinguish between smoking, vaping, or consuming edibles, meaning researchers could not determine whether one method was associated with more hospitalizations than another.
Previous research has raised similar concerns about legal marijuana and cardiovascular health. A 2024 study published in the Journal of the American Heart Association analyzed survey responses from 434,104 American adults. Researchers found that people who reported using cannabis daily had 25% higher odds of reporting a heart attack and 42% higher odds of reporting a stroke compared with nonusers.
Those associations remained after researchers accounted for tobacco use and other cardiovascular risk factors. However, the findings were observational and relied on self-reported information. They did not establish that marijuana directly caused the reported medical conditions.
The American Heart Association has also warned that cannabis may present particular concerns for people with existing heart disease. Someone managing high blood pressure, an irregular heartbeat, or another cardiovascular condition should discuss cannabis use with their healthcare provider. Marijuana can interact with certain medications, including some blood thinners and drugs used to manage heart conditions.
Doctors also recommend taking unexplained cardiovascular symptoms seriously. A racing heartbeat, recurring dizziness, shortness of breath, or unusual fatigue can warrant medical evaluation. Chest pressure, pain spreading into the arms or jaw, cold sweats, or sudden breathing difficulties can signal a heart attack. The American Heart Association advises calling 911 for possible heart attack symptoms rather than waiting for them to disappear.
For people who experience heart palpitations or chest discomfort after using legal marijuana, discussing the timing and frequency of those symptoms with a medical professional can help identify possible causes. A clinician may need to evaluate other risk factors, medications, or underlying conditions before determining whether cannabis might be contributing.
The researchers behind the new study are calling for more detailed investigations into how cannabis products, consumption methods, and legalization policies affect cardiovascular health. Their analysis cannot determine whether marijuana caused a particular person’s heart problems, but it identifies measurable increases in several serious heart-related hospitalization rates following the expansion of recreational sales.
As more adults gain legal access to marijuana, questions about its potential effects on heart health remain unresolved, particularly for frequent users and people with preexisting cardiovascular conditions.
