Smoking marijuana causes heart disease

Warning of stroke by cannabis cardiologists

Cannabis is the most commonly used recreational drug: In the United States, more people now smoke cannabis than tobacco. The drug is said to have a healing or soothing effect on various diseases, so some patients also experiment with cannabis. In exceptional cases, doctors can legally prescribe it for the treatment of chronic pain, epilepsy, seizures or as an adjunct to chemotherapy.

The drug is mostly smoked in the form of marijuana (crushed and dried cannabis flowers and leaves), but increasingly, THC users are also inhaling THC via e-cigarette or water pipe, which increases the amount consumed. The intoxicating effect is thanks to the ingredient tetrahydrocannabiol (THC), which also relaxes the muscles, has a calming effect and is said to suppress nausea. Over the past 30 years, THC levels in marijuana have tripled. At high doses, intoxication can lead to palpitations and even circulatory collapse. But the drug is also harmful in the long term.

What was observed

American cardiologists noticed that an increasing number of young people with heart attacks who had taken cannabis regularly were coming to the emergency room. This gave the concerned medical professionals an opportunity to carry out an up-to-date evaluation of what has been found so far about the drug's influence on cardiovascular health. Research on this is difficult because cannabis is illegal in many countries, so most findings can only be based on medical observations and voluntary reports on drug use.

The results of various observational studies suggest an association between marijuana use and a range of cardiovascular risks.

Harmful like smoking tobacco

First of all, marijuana smoking poses many of the same health risks as tobacco smoking because the smoke contains many of the same cardiovascular damaging substances, warns Muthiah Vaduganathan of Brigham and Women's Hospital in Boston. Joints in particular (cannabis mixed with tobacco) are often inhaled more deeply than cigarettes, so even more of the risky substances get into the lungs.

Increased risk of stroke

Using survey data from over 40,000 young adults who regularly smoked cannabis, researchers calculated that they were twice to three times more likely to suffer a stroke than young adults who did not use cannabis. Other colleagues observed cramps and constrictions and other dysfunction of the blood vessels while examining the brains of heavy, chronic cannabis users. High blood pressure and blockage of arteries by blood clots were more common among young cannabis smokers.

Heart attack risk

The risk of heart attack may also be increased, because cannabis use causes the pulse and blood pressure to skyrocket and in the long term can damage blood vessels, constrict veins in a spasmodic manner and cause increased blood platelets to clump. It is believed that the drug also damages the heart muscle directly, thereby impairing pump function.

In addition, an increased number of cardiac arrhythmias (including atrial fibrillation) were observed in cannabis smokers.

Why is cannabis particularly dangerous for cardiovascular patients?

So cannabis seems to damage the heart and circulation - the more and the more often it is used, the greater the risk. What is bad news for young, healthy people can be fatal for cardiovascular patients.

For these patients, there are also interactions of THC with often prescribed cardiovascular medication, e.g. B. statins and blood thinners. Cannabis can change or intensify the effects of these drugs, so that, for example, patients who are treated with blood-thinning drugs (e.g. Marcumar) could have life-threatening bleeding.

In people with pre-existing coronary artery disease, cannabis can trigger angina pain, a small experimental study found.


Even if the data situation is quite weak: If you are already struggling with cardiovascular problems, you should better keep your hands off cannabis or limit its use, according to the opinion of the cardiologists.

  • About this article

    Author: Editor, Dr. Corinna Powell

    Created: 6.2.2020


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    • Parekh T et al. Marijuana Use Among Young Adults (18-44 Years of Age) and Risk of Stroke. A Behavioral Risk Factor Surveillance System Survey Analysis. Stroke 2020; 51: 308-310
    • "Cannabis products: hashish, marijuana";

    Credit: Cover picture © Petra Bork /