By Sherrie Khadanga, MD

More people across the country are using cannabis both for medicinal and recreational purposes. As of last year, medical marijuana is legalized in 36 states while recreational use is approved in 18. With more people using marijuana for medicinal purposes such as  chemotherapy-induced nausea, glaucoma, or cachexia, this has led to a more general acceptance of the drug, which is often viewed as less harmful than other substances. In a recent survey from the National Center for Drug Abuse Statistics, 72% of Americans believe regular alcohol use to be more harmful than regular marijuana use; and when comparing marijuana to tobacco, 76% report that tobacco is worse than marijuana.¹ While the public may perceive marijuana as being relatively harmless, that is far from the case — particularly when it comes to cardiovascular health.

Effect of THC

Tetrahydrocannibinol, otherwise known as THC, is the main psychoactive ingredient found in marijuana. It acts on receptors throughout the cardiovascular system, causing an increase in both heart rate and blood pressure.² Additionally, it has been shown that THC can damage the endothelial cells that line the blood vessels, resulting in reduced blood flow.³ These effects increase the risk for myocardial infarction, arrhythmias like atrial fibrillation, and stroke. Those who use marijuana daily have a 25% higher risk of heart attack and 42% higher risk of stroke compared to nonusers.⁴ A recent study found that adults younger than age 50 who use marijuana are six times more likely to experience a heart attack compared to nonusers.⁴ While the risk of heart attack increases with daily marijuana consumption, the risk is considerably higher in the hour following marijuana use.⁵ Additionally, multiple studies have found that those with preexisting heart disease are more susceptible to the cardiovascular complications from marijuana compared to those without heart disease.^4,5

Delivery of Marijuana: Is One Method Safer Than Another?

THC can be administered in variety of ways, either through inhalation, ingestion, or transdermal delivery. Typically, if marijuana is inhaled either through smoking or vaping, the effect is more rapid and temporary while for oral ingestion (edibles, oils) the effect is slower but has a longer duration.² Despite the risks, many continue to consume marijuana, often posing the question “which way is safer?” There is no “safe route” for marijuana use; however, if one decides to use, it is typically advised to avoid smoking to minimize lung injury. If edibles or topical ointments are used, then it is recommended to use the lowest dose possible and to limit frequency. Even if needed for medical purposes, marijuana dispensaries are not regulated by the FDA; therefore, the strength and ingredients in marijuana can differ quite a bit.¹

Cardiopulmonary Rehabilitation: An Opportunity to Engage in Conversation

At the initial assessment, it is vital that cardiopulmonary rehabilitation professionals ask patients directly if they use marijuana and, if so, is it for medicinal or recreational purposes? How is it used — through smoking or via an edible? It is important to discuss the potential implications for the patient, particularly if someone has had a recent myocardial infarction and is continuing to use marijuana. As part of the care team, we should advise patients to abstain from cannabis use; but if it is needed, for example as an appetite stimulant in a cancer patient, then we should encourage the patient to speak to their physician about limiting the dosage and frequency in order to minimize the adverse effects on the heart.

While it may seem that marijuana can provide a calm peace of mind, be aware that in reality, it will only cause heartache in the long run.

Sherrie Khadanga, MD, is an Associate Professor of Medicine at the University of Vermont Larner College of Medicine and serves as the Director of Cardiac Rehabilitation at University of Vermont Medical Center in Burlington, Vermont. As a clinical cardiologist and NIH-funded researcher, her work focuses on improving access and outcomes in cardiac rehab — particularly in women.  

REFERENCES

1. https://drugabusestatistics.org/marijuana-addiction/
2. Khadanga S, Ades PA. What do we tell patients with coronary artery disease about marijuana use?. Coron Artery Dis. 2018;29(1):1-3. doi:10.1097/MCA.0000000000000567
3. Mohammadi L, Navabzadeh M, Jiménez-Téllez N, et al. Association of endothelial dysfunction with chronic marijuana smoking and THC-edible use. JAMA Cardiol. 2025;10(8):851-855. doi:10.1001/jamacardio.2025.1399
4. Jeffers AM, Glantz S, Byers AL, Keyhani S. Association of cannabis use with cardiovascular outcomes among US adults. J Am Heart Assoc. 2024;13(5):e030178. doi:10.1161/JAHA.123.030178
5. Kamel I, Mahmoud AK, Twayana AR, Younes AM, Horn B, Dietzius H. Myocardial infarction and cardiovascular risks associated with cannabis use: a multicenter retrospective study. JACC Adv. 2025;4(5):101698. doi:10.1016/j.jacadv.2025.101698
6. Mittleman MA, Lewis RA, Maclure M, Sherwood JB, Muller JE. Triggering myocardial infarction by marijuana. Circulation. 2001;103(23):2805-2809. doi:10.1161/01.cir.103.23.2805