Heart risks from cannabis remain hazy but warrant caution
News briefs
- Reviewed by Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
The widespread legalization of cannabis in the United States has spurred greater use of marijuana and its active components, tetrahydrocannabinol (THC) and cannabidiol (CBD). How do these psychoactive substances affect the heart? A review of recent research, published in the July 2026 issue of Trends in Cardiovascular Medicine, summarized the current evidence.
The analysis, which included studies published from 2014 to mid-2025, found conflicting evidence regarding any links between cannabis and heart-related problems, including heart attacks, strokes, coronary artery disease, and heart failure. The most consistent association was between cannabis use and heart rhythm problems.
Studying the effects of cannabis is challenging, given the differences in how people use the drug (smoking, vaping, or ingesting), how much they use at a time, and how often they use it. Both recreational and medical cannabis products contain varying ratios of THC and CBD. THC, which is primarily responsible for the euphoric effects of cannabis, increases heart rate, blood pressure, and the heart’s oxygen demand. In contrast, CBD’s effects may include decreasing inflammation and anxiety. Finally, many people who use cannabis also use tobacco, alcohol, or opioids, which makes it difficult to isolate cannabis-specific effects.
According to national surveys, daily or near-daily use of cannabis is now more common than daily or near-daily alcohol use, with the highest prevalence of cannabis use among younger males. Recent trends suggest rising use among older adults and females as well.
An editorial accompanying the study highlighted such questions as whether cannabis use during adolescence (when heart disease risk is low) is more or less risky than using cannabis at an older age (when heart disease risk is higher). Until higher-quality data are available, people who use cannabis should do so with caution, especially if they have heart disease or risk factors for it.
Image: © skodonnell/Getty Images
About the Author
Julie Corliss, Executive Editor, Harvard Heart Letter
About the Reviewer
Robert H. Shmerling, MD, Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
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