Cannabis Use Shows Substantial Risks, No Benefits for Cardiovascular Health

Marijuana Various

Marijuana. Credit: Copyright American Heart Association

  • Observational studies have found no cardiovascular benefits associated with cannabis use.
  • Cannabis use may be linked to an increased risk of heart attacks, atrial fibrillation and heart failure; however, additional studies need to be conducted to better understand the research findings.
  • Cannabis is classified as a Schedule I drug by the U.S. Drug Enforcement Agency (DEA), which severely limits scientists from studying it.

The chemicals in cannabis have been linked to an increased risk of heart attacks, heart failure and atrial fibrillation in observational studies; however, a full understanding of how use of cannabis affects the heart and blood vessels is limited by a lack of adequate research, according to a new Scientific Statement from the American Heart Association (AHA) published today in its flagship journal Circulation.

According to the statement, although cannabis, also known as marijuana, may be helpful for conditions such as spasticity associated with multiple sclerosis, among others, cannabis does not appear to have any well-documented benefits for the prevention or treatment of cardiovascular diseases. Preliminary studies have found that cannabis use could negatively impact the heart and blood vessels.

Dried Marijuana Cigarette

Marijuana Cigarette. Credit: Copyright American Heart Association

“Attitudes towards recreational and medicinal use of cannabis have changed rapidly, and many states have legalized it for medical and/or recreational use. Health care professionals need a greater understanding of the health implications of cannabis, which has the potential to interfere with prescribed medications and/or trigger cardiovascular conditions or events, such as heart attacks and strokes,” said Robert L. Page II, Pharm.D., M.S.P.H., FAHA, chair of the writing group for the statement and 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.

A recent study cited in the statement suggests that cannabis use is present in 6% of heart attack patients under 50 years of age. Another study found that cannabis users ages 18 to 44 had a significantly higher risk of having a stroke compared to nonusers. “Unfortunately, most of the available data are short-term, observational and retrospective studies, which identify trends but do not prove cause and effect,” said Page.

The most common chemicals in cannabis include THC (tetrahydrocannabinolic acid), the component of the plant that induces a “high,” and CBD (cannabidiol), which can be purchased over the counter, but to date, the FDA has only approved one CBD-derived product. Importantly, the FDA has not approved any other cannabis, cannabis-derived, or cannabidiol (CBD) products currently available on the market.

Robert L. Page

Robert L. Page II Pharm.D. M.S.P.H. FAHA. Chair of the writing group for the statement and 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. Credit: Copyright University of Colorado

Some studies have found that within an hour after cannabis is smoked, THC may induce heart rhythm abnormalities, such as tachycardia, premature ventricular contractions, atrial fibrillation and ventricular arrhythmias. Acutely, THC also appears to stimulate the sympathetic nervous system, which is responsible for the “fight or flight” response, resulting in a higher heart rate, a greater demand for oxygen by the heart, higher blood pressure while laying down and dysfunction within the walls of the arteries.

In contrast, studies on CBD, which does not produce a “high” or intoxication, have found associations with reduced heart rate, lower blood pressure, increased vasodilation (ability of the arteries to open), lower blood pressure and potentially reduced inflammation. Inflammation is linked to atherosclerosis, the slow narrowing of the arteries that underlies most heart attacks and, possibly strokes.

Smoking and inhaling cannabis, regardless of THC content, has been associated with cardiomyopathy (heart muscle dysfunction), angina (chest pain), heart attacks, heart rhythm disturbances, sudden cardiac death, and other serious cardiovascular conditions. In states where cannabis has been legalized, an increase in hospitalizations and emergency department visits for heart attacks has been observed.

The way cannabis is consumed may influence how it affects the heart and blood vessels. “Many consumers and health care professionals don’t realize that cannabis smoke contains components similar to tobacco smoke,” said Page. Smoking and inhaling cannabis, regardless of THC content, has been shown to increase the concentrations of blood carboxyhemoglobin (carbon monoxide, a poisonous gas) five-fold, and a three-fold increase in tar (partly burnt combustible matter), similar to the effects of inhaling a tobacco cigarette.

Carbon monoxide intoxication from inhaled tobacco or cannabis has been associated with several heart problems, such as heart muscle disease, chest pain, heart attacks, heart rhythm disturbances, and other serious conditions.  

Cannabis use should be discussed in detail with a health care professional so that an individual’s potential health risks can be reviewed. “If people choose to use cannabis for its medicinal or recreational effects, the oral and topical forms, for which doses can be measured, may reduce some of the potential harms. It is also vitally important that people only use legal cannabis products because there are no controls on the quality or the contents of cannabis products sold on the street,” said Page.

In addition to the poisonous compounds in cannabis smoke, vaping cannabis may also result in serious health outcomes, especially when it is mixed with vitamin E acetate oils, which are linked to EVALI (e-cigarette or vaping product use-associated lung injury), the potentially fatal illness that emerged among e-cigarette users last year.

“People who use cannabis need to know there are potentially serious health risks in smoking or vaping it, just like tobacco smoke. The American Heart Association recommends that people not smoke or vape any substance, including cannabis products, because of the potential harm to the heart, lungs and blood vessels,” said Rose Marie Robertson, M.D., FAHA, the deputy chief science and medical officer for the American Heart Association and co-director of the AHA Tobacco Center for Regulatory Science.

The statement also discusses cannabis use among older adults, people diagnosed with cardiovascular diseases and other populations including youth. Some studies have suggested that cannabis use – both CBD and THC – may be safe and effective for older populations. Though they are the least likely to use cannabis, older adults often use it to reduce neuropathic pain (common among people with type 2 diabetes), improve quality of life and decrease prescription drug use (including opioids).

Additionally, benefits for patients with age-related diseases, including Parkinson’s and Alzheimer’s, have also been reported in some studies; however, there is very little research on the long-term effects of cannabis use among this group of people. Another concern about older adults using cannabis is the potential of interactions with other medications, including blood thinners (anti- coagulants), anti-depressants, antipsychotics, antiarrhythmics for heart rhythm abnormalities, and statin drugs, which reduce cholesterol levels.

For people diagnosed with heart disease, cannabis should be used with extreme caution because cannabis increases the heart’s need for oxygen at the same time as it decreases available oxygen supply, which could cause angina (chest pain). In addition, in some studies, cannabis triggered a heart attack in people with underlying heart disease. Other studies have linked cannabis use to a higher risk of strokes and heart failure.

Research into the effects of cannabis on the heart and blood vessels has been limited because cannabis is categorized as a Schedule I controlled substance by the U.S. Drug Enforcement Agency (DEA). Schedule I controlled substances are defined as having no accepted medical use, a high potential for abuse and an unacceptable safety profile. The AHA’s Scientific Statement suggests that the DEA remove cannabis from the Schedule I of the U.S. Controlled Substances Act so that it can be widely studied by scientists. Forty-seven U.S. states, the District of Columbia, and 4 of 5 U.S. territories allow some form of cannabis use, and its use has risen considerably over the past decade, particularly among people 18-25 years of age. Although many states have legalized medical and/or recreational cannabis use, cannabis growing, sales and use are illegal at the federal level, further complicating scientific research.

“We urgently need carefully designed, prospective short- and long-term studies regarding cannabis use and cardiovascular safety as it becomes increasingly available and more widely used,” Page said. “The public needs fact-based, valid scientific information about cannabis’s effect on the heart and blood vessels. Research funding at federal and state levels must be increased to match the expansion of cannabis use – to clarify the potential therapeutic properties and to help us better understand the cardiovascular and public health implications of frequent cannabis use.”

Legalization of cannabis for medical purposes should align with patient safety and efficacy. Legalization for recreational use will remain a significant concern until more research can be conducted on the safety and long-term population health effects across the life course and the equity and social justice impact of these laws. In those states where cannabis is legal for recreational or medical purposes, there should be a robust public health infrastructure that is adequately funded and implemented to minimize its impact on CVD mortality especially among young people those who have heart disease. The statement calls for the federal government to create standardized labeling about the amount of THC and CBD and require it on all legal cannabis products.

The Association believes cannabis should be tightly integrated into comprehensive tobacco control and prevention efforts that include age restrictions for purchasing, retailer compliance, excise taxes, comprehensive smoke-free air laws, professional education, screening within the clinical environment – for example, when a patient is admitted to the hospital and routinely screened to avoid medication interactions or potential toxicity – and coverage of cessation treatment programs by insurers, Medicare and Medicaid. These efforts should be adequately funded, and at least some portion of the revenue from cannabis taxation should be directed toward programs and services that improve public health.

The statement was written on behalf of the American Heart Association’s Clinical Pharmacology and Heart Failure and Transplantation Committees of the Council on Clinical Cardiology; the Council on Basic Cardiovascular Sciences; the Council on Cardiovascular and Stroke Nursing; the Council on Epidemiology and Prevention; the Council on Lifestyle and Cardiometabolic Health; and the Council on Quality of Care and Outcomes Research.

Reference: “Medical Marijuana, Recreational Cannabis, and Cardiovascular Health: A Scientific Statement From the American Heart Association” by Robert L. Page II, Larry A. Allen, Robert A. Kloner, Colin R. Carriker, Catherine Martel, Alanna A. Morris, Mariann R. Piano, Jamal S. Rana, Jorge F. Saucedo, and On behalf of the American Heart Association Clinical Pharmacology Committee and Heart Failure and Transplantation Committee of the Council on Clinical Cardiology; Council on Basic Cardiovascular Sciences; Council on Cardiovascular and Stroke Nursing; Council on Epidemiology and Prevention; Council on Lifestyle and Cardiometabolic Health; and Council on Quality of Care and Outcomes Research, 5 August 2020, Circulation.
DOI: 10.1161/CIR.0000000000000883

Co-authors are Larry A. Allen, M.D., M.H.S., FAHA, (vice chair); Robert A. Kloner, M.D., Ph.D.; Colin R. Carriker, Ph.D.; Catherine Martel, Ph.D.; Alanna A. Morris, M.D., M.Sc., FAHA; Mariann R. Piano, R.N., Ph.D., FAHA; Jamal S. Rana, M.D., Ph.D.; Jorge F. Saucedo, M.D., FAHA. Author disclosures are in the manuscript.

4 Comments on "Cannabis Use Shows Substantial Risks, No Benefits for Cardiovascular Health"

  1. WOW! It’s 2020 and our government still hasn’t figured out what with pot? Go ask the pot heads and find out! First of all with the hydro type of pot there is an extreme rush one may get when one smokes it after not smoking it for the last 3-6 days. People with health conditions have to be careful because the high can send the body through stages of actions that can increase heart rate, anxiety, fear of being too high, heart pulsations, flushes, sweats and more. It seems that maybe diabetics may have problems with their blood sugar and may experience some adverse effects when smoking pot when they haven’t for a while. People who smoke pot a lot don’t get that kind of a high that someone gets one they smoke only every so often. It’s like the body builds up a resistance to getting super high as you smoke pot more. Pot smokers rarely get deadly sick from pot and most medical episodes caused by pot go away after an hour or so after one comes down from the extreme high of the pot. From what I know there has been no noticeable amount of pot smokers ending up with lung cancer or other medical problems from pot. It will make you lazy but that isn’t a medical problem. Pot just makes one want to sit back and enjoy the moment. Find out more at

  2. Carolyn L Zaremba | August 5, 2020 at 11:56 am | Reply

    I started smoking pot in the 1960s and still do on occasion. This article first declares that cannabis causes heart problems, but immediately follows that declaration with the fact that they are not allowed to research it!! Am I supposed to believe this nonsense? Studies in other countries have found many benefits to cannabis use. This article smells like anti-pot propaganda to me.

  3. Michele Medley | August 10, 2020 at 7:04 am | Reply

    I stopped all the Multiple sclerosis medicines prescribed due to severe side effects, and decided to go on natural herbal approach. My primary care provider introduced me to Mayaka Herbal Clinic and i immediately started on their Multiple Sclerosis herbal formula treatment, this herbal treatment has made a tremendous difference for me. My symptoms including shaking, muscle weakness, fatigue, mood swings, numbness, double vision and urinary retention all disappeared after the 4 months treatment! Their website is w w w. mayakaherbalclinic. c o m. Its just amazing!

  4. I think there are many laboratory tests that directly show exactly how smoking affects the cardiovascular system. In fact, any smoking has this effect on a person. Therefore, it is very important to read more information. That the time spent smoking cannabis is much less than smoking cigarettes, despite all the claims.

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