Legalization of marijuana, for both medical and recreational use, is on the rise across the U.S. The American Heart Association, the world's leading nonprofit organization focused on heart and brain health for all, warns that using marijuana may increase your risk of deadly cardiovascular diseases, heart attacks and strokes, according to research evidence noted in two scientific statements published by the Association.
The Association's 2020 scientific statement Medical Marijuana, Recreational Cannabis, and Cardiovascular Health, notes that while marijuana, also known as cannabis, may be helpful for some other medical conditions, it does not appear to have any well-documented benefits for the prevention or treatment of cardiovascular diseases (CVD). In fact, the chemicals in cannabis have been linked to an increased risk of heart attacks, heart failure and atrial fibrillation in observational studies.
Marijuana users may also have an increased risk of clot-caused stroke, according to the American Heart Association's 2022 scientific statement, Use of Marijuana: Effect on Brain Health. Studies cited in the statement found people who used marijuana had more strokes - as much as 17% to 24% more – compared to those who did not use.
"There is a lot of confusion about the benefits vs. the dangers of marijuana use, and much of that depends on the ingredients in and the method of use of the product," said Robert L. Page II, Pharm.D., M.S.P.H., FAHA, volunteer chair of the writing group for the statement on medical and recreational marijuana and CVD. "The most common chemicals in cannabis include THC, or tetrahydrocannabinolic acid, the psychoactive component of the plant that induces a "high," and CBD, or cannabidiol, which can be purchased over the counter. These chemicals may be working at cross purposes, as some studies suggest CBD could reduce heart rate and blood pressure, while others found THC may raise heart rate and blood pressure. Many marijuana products are becoming increasingly potent with higher levels of THC, which is very concerning."
Smoking and inhaling marijuana, regardless of THC content, has been associated with heart muscle dysfunction, chest pain, heart attacks, heart rhythm disturbances, sudden cardiac death and other serious cardiovascular conditions. In U.S. states where cannabis has been legalized, an increase in hospitalizations and emergency department visits for heart attacks has been observed, according to the American Heart Association's 2020 scientific statement on cannabis use and cardiovascular health.
"The way cannabis is consumed may make a difference in how it affects the heart and blood vessels. Many people don't realize that cannabis smoke contains components similar to tobacco smoke," said Page, who is a professor in the department of clinical pharmacy and the department of physical medicine/rehabilitation at the University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences in Aurora, Colorado. "Smoking and inhaling cannabis, regardless of THC content, has been shown to increase the concentrations of poisonous carbon monoxide and tar in the blood similar to the effects of inhaling the smoke from a tobacco cigarette. Also, limited information exists on the hazards of exposure to secondhand cannabis smoke. According to the U.S. Centers for Disease Control and Prevention, THC can be passed to infants and children through secondhand smoke, and people exposed to secondhand marijuana smoke can experience psychoactive effects.""
More recent research published supports the evidence reported in the earlier scientific statements:
- A new study presented at the American Heart Association's Epidemiology and Lifestyle 2023 meeting found that vaping THC was associated with self-reported symptoms of depression and anxiety, even more so than vaping nicotine.
- A recent study from Stanford University researchers found that people who reported using marijuana daily were 34% more likely to be diagnosed with coronary heart disease, compared to those who reported no history of cannabis use.
"The federal government still classifies marijuana as a Schedule 1 drug 'with no currently accepted medical use and a high potential for abuse.' That means researchers face tight restrictions on conducting rigorous controlled trials with marijuana products," Page said. "So much of what we do know about cannabis use is based on data from short-term, observational and retrospective studies, which identify trends but do not prove cause and effect. Until we know more definitively the specific pros and cons of marijuana use, people need to be aware of the potential dangers."
Page recommends people who do choose to use marijuana for medicinal or recreational effects should:
- Only use legal cannabis products because there are no controls on the quality or the contents of cannabis products sold on the street.
- Note that the dosage of cannabis in the oral and topical forms can be quantified, so this may possibly reduce some of the potential harms with inadvertent high dosages.
- Be open with your doctor about any marijuana use as it relates to your overall health, even though it may be a sensitive topic, because it will help to better understand how that might interfere with prescribed medications or trigger cardiovascular conditions or events, such as heart attacks and strokes.
"Attitudes towards recreational and medicinal use of marijuana are changing rapidly, and more states are continuing to move to have it legalized," Page said. "However, there is still too much unknown, and I would urge anyone currently or considering using cannabis proceed with extreme caution.
Learn more about the importance of heart health at heart.org.
