A new study led by researchers at UC San Francisco has found that chronic cannabis use—whether smoked or eaten—may pose significant risks to heart and blood vessel health.
Published on May 28 in JAMA Cardiology, the study revealed that regular marijuana users had reduced blood vessel function similar to that seen in tobacco smokers, raising concerns about long-term cardiovascular effects.
The research team studied 55 adults who were outwardly healthy but had used cannabis at least three times a week for a year or more. These participants did not use nicotine or other tobacco products, allowing researchers to isolate the effects of cannabis.
On average, marijuana smokers in the study had used it for about 10 years, while those who consumed edibles had done so for about 5 years.
The key finding was that both forms of cannabis use were associated with impaired vascular function—a measure of how well blood vessels expand and contract. In fact, vascular function was reduced by about half in cannabis users compared to non-users. Reduced function in blood vessels can increase the risk of serious conditions such as heart attacks, high blood pressure, and stroke.
Interestingly, the study also looked at the impact of cannabis on endothelial cells, which line the inside of all blood vessels and are crucial for keeping the cardiovascular system healthy. In those who smoked cannabis, researchers found harmful changes in the blood that could damage these cells.
However, those who used edibles did not show this particular change—suggesting that smoking may introduce additional harmful substances that edibles do not.
It’s still unclear exactly how THC—the main psychoactive compound in marijuana—affects blood vessels, especially when consumed in edible form. The study’s authors believe different mechanisms may be at play depending on how the cannabis is consumed.
Smoking introduces various byproducts from combustion, which may harm blood vessels directly, while ingested THC may impair vascular health through other, less understood pathways.
“These findings highlight the need to understand that marijuana use—just like tobacco—can have significant effects on heart and blood vessel health,” said Dr. Leila Mohammadi, the study’s first author. Senior author Dr. Matthew L. Springer added that while cannabis is often viewed as safer than tobacco, this study challenges that assumption, especially when it comes to long-term use.
As cannabis becomes more widely legalized and used recreationally and medicinally, these findings underline the importance of public health awareness. The study suggests that regular cannabis users—particularly those who smoke it—should be aware of potential cardiovascular risks and speak with their healthcare providers about monitoring their heart health.
More research is needed to fully understand the long-term effects of cannabis on the cardiovascular system, especially as patterns of use continue to evolve. But for now, this study offers a strong warning: cannabis, whether smoked or eaten, is not without consequences when it comes to heart health.
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The study is published in JAMA Cardiology.
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