Marijuana and Heart Disease: What You Need to Know

As marijuana becomes legal in more places across the United States, it's important to understand how it affects your heart. Recent research shows that using marijuana can increase your risk of serious heart problems, including heart attacks, strokes, and irregular heartbeats. I get asked about this frequently on social media, and we have very robust data now.

How Marijuana Affects Your Heart

When you use marijuana, the main active ingredient called THC affects your body in several ways that can harm your heart. It activates your sympathetic nervous system, which is like your body's "fight or flight" response. This makes your heart beat faster and work harder, increasing how much oxygen your heart needs. At the same time, marijuana can cause the blood vessels in your heart to tighten up (called vasospasm), making it harder for blood to flow. It can also damage the lining of your blood vessels and make your blood more likely to form clots.

Mechanisms Of Marijuana And Heart Attacks

The mechanisms underlying these cardiovascular effects include THC-induced sympathetic nervous system activation, increased myocardial oxygen demand, coronary vasospasm, endothelial dysfunction, and platelet activation.

Marijuana And Carbon Monoxide Poisoning

If you smoke marijuana, there's an additional problem. The smoke contains carbon monoxide, the same dangerous gas found in car exhaust. This carbon monoxide can increase to five times the normal level in your blood, which further stresses your heart and damages your cells.

When cannabis is smoked, additional harm comes from carbon monoxide exposure, which increases carboxyhemoglobin levels 5-fold compared to baseline and contributes to oxidative stress. 

Let's take a look at how much more likely you are to have a cardiovascular event f you smoke weed versus those who do not smoke weed.

Odd Ratios With 95% CIs for Cardiovascular Outcomes in Cannabis Users Compared to Nonusers MACE = major adverse cardiovascular events; MI = myocardial infarction.

Looking at the very top blue line, this means that you are 6.3 times more likely to have an "MI" (myocardial infarction, heart attack), if you smoke marijuana, compared to non smokers.

Weed Increase Heart Attack Risk 6 Times Normal

Cannabis use is associated with a 6-fold increased risk of myocardial infarction in relatively healthy adults aged 50 years or younger without traditional cardiovascular risk factors (0.55% vs 0.09% absolute risk).

The risk appears temporally related to use, the risk of MI increases 4.8-fold within 60 minutes after cannabis consumption.

Among young patients presenting with first MI before age 50, over 6% report cannabis use, and these users have twice the hazard of death even after adjusting for tobacco.

The Risk of Heart Attacks

One of the most concerning findings is that marijuana use significantly increases the risk of heart attacks, especially in younger, otherwise healthy people. Studies show that people under 50 who use marijuana have a six times higher risk of having a heart attack compared to non-users. The risk is highest right after using marijuana, within the first hour, your risk of having a heart attack increases nearly five-fold.

Among young people who have their first heart attack before age 50, more than 6% report using marijuana. Even more worrying, these marijuana users have twice the risk of dying compared to non-users, even when researchers account for tobacco smoking.

Strokes and Other Heart Problems

Marijuana doesn't just affect your risk of heart attacks. Large studies combining data from many research papers show that marijuana users have a 20% higher risk of stroke and more than double the risk of dying from heart-related causes. People who use marijuana also develop irregular heartbeats more often, with nearly 3% of hospitalized marijuana users experiencing heart rhythm problems like atrial fibrillation.

Meta-analysis demonstrates cannabis use is associated with a 20% increased risk of stroke (RR 1.20, 95% CI 1.13-1.26) and a 2.1-fold increased risk of cardiovascular death (RR 2.10, 95% CI 1.29-3.42).
Cannabis users also show increased rates of arrhythmias, particularly atrial fibrillation, with 2.7% of hospitalized cannabis users developing arrhythmias.

Does How You Use Marijuana Matter?

Yes, it does. Smoking marijuana carries a much higher risk to your heart than other ways of using it. People who frequently smoke marijuana have more than twice the risk of heart attacks and nearly twice the risk of strokes compared to non-users. However, when researchers looked at people who use marijuana in other forms, like vaping or eating edibles, they found no significant increase in heart problems. This suggests that much of the danger comes from the smoke itself, not just the THC.

We know from smoking, that it is the smoke in your lungs that triggers atherosclerosis. You could be smoking anything. Nicotine has it's own intrinsic properties that make it worse because it causes vasoconstriction, but other smoked substances have similar cardiovascular risk effects due to the smoking alone.

Smoked cannabis carries significantly higher cardiovascular risk than other forms of consumption.

Frequent marijuana smoking is associated with 6.3 times higher odds of MI and 4.3 times higher odds of stroke.

In contrast, cannabis use in forms other than smoking (vaping, edibles) shows no statistically significant association with cardiovascular events.

What This Means for You

Major medical organizations, including the American Heart Association and the American College of Emergency Physicians, now recommend that doctors consider marijuana use as a risk factor for heart disease. If you're thinking about using medical marijuana, doctors should check your heart health first. If you already use marijuana and have heart disease or risk factors like high blood pressure or diabetes, it's especially important to talk with your doctor.

The good news is that there are ways to reduce your risk. Using lower doses, avoiding smoking (choosing edibles or other forms instead), and watching for warning signs like chest pain or heart palpitations, especially within an hour or two after use, can help protect your heart. Most importantly, if you have heart disease or risk factors, working with your doctor to manage those risks is crucial.

Clinical Implications Of Marijuana

The American Heart Association recommends that clinicians assess cardiovascular risk before prescribing medical cannabis.

The American College of Emergency Physicians advises physicians to consider medical cannabis use a risk factor for cardiovascular events including acute coronary syndrome and stroke.

Clinicians should optimize treatment of traditional cardiovascular risk factors, counsel on lower-dose formulations, and monitor for symptoms like palpitations or chest pain, especially within 1-2 hours after use when adverse effects peak.

The Bottom Line

While marijuana may seem harmless to many people, the evidence is clear that it can seriously affect your heart health. The risks are real and can be life-threatening, particularly for people who smoke marijuana or use it frequently. As marijuana becomes more widely available, it's essential to understand these risks and make informed decisions about your health. If you use marijuana or are considering it, talk to your doctor about how it might affect your heart, especially if you have any existing heart problems or risk factors.

References

1. Kamel I, Mahmoud AK, Twayana AR, et al. Myocardial Infarction and Cardiovascular Risks Associated With Cannabis Use: A Multicenter Retrospective Study. JACC Advances. 2025;4(5):101698.

2. Hsu M, Shah A, Jordan A, Gold MS, Hill KP. Therapeutic Use of Cannabis and Cannabinoids: A Review. JAMA. 2025.

3. DeFilippis EM, Bajaj NS, Singh A, et al. Marijuana Use in Patients With Cardiovascular Disease: JACC Review Topic of the Week. Journal of the American College of Cardiology. 2020;75(3):320-332.

4. Page RL, Allen LA, Kloner RA, et al. Medical Marijuana, Recreational Cannabis, and Cardiovascular Health: A Scientific Statement From the American Heart Association. Circulation. 2020;142(10):e131-e152.

5. Storck W, Elbaz M, Vindis C, et al. Cardiovascular Risk Associated With the Use of Cannabis and Cannabinoids: A Systematic Review and Meta-Analysis. Heart. 2025.

6. Shah S, Patel S, Paulraj S, Chaudhuri D. Association of Marijuana Use and Cardiovascular Disease: A Behavioral Risk Factor Surveillance System Data Analysis of 133,706 US Adults. The American Journal of Medicine. 2021;134(5):614-620.

7. van Amsterdam J, van den Brink W. Cannabis Use Variations and Myocardial Infarction: A Systematic Review. Journal of Clinical Medicine. 2024;13(18):5620.

8. American College of Emergency Physicians Clinical Policies Subcommittee on Cannabis Consumption, Hatten BW, Bonney C, et al. Clinical Policy: Critical Issues Related to Harms of Cannabis Exposure in Adult Patients Presenting to the Emergency Department, Cardiovascular Considerations. Annals of Emergency Medicine. 2026;87(1):e1-e9.