Does marijuana affect your heart


Marijuana and heart health: What you need to know

Access to marijuana is growing, but marijuana benefits and its risks have not been carefully studied.

Updated: June 24, 2019Published: August, 2017

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In many states in this country, you can legally use marijuana for a range of health benefits, including the treatment of chronic pain, anxiety, and nausea. Smoking is the fastest way to feel the effects of marijuana, which is derived from the Cannabis sativa plant. Yet marijuana smoke contains many of the same toxins, irritants, and carcinogens found in cigarette smoke — a known contributor to heart disease as well as cancer.

Marijuana cultivation and use dates back some 6,000 years. However, the cardiovascular and other health effects of cannabis aren’t well studied. That’s partly because under federal law, cannabis is a Schedule I substance, meaning it has “no currently accepted medical use and a high potential for abuse.” That designation places numerous restrictions on researchers, making it difficult to carry out rigorous research on marijuana.

“As a result, everything we’re told about what marijuana does or doesn’t do should be viewed with a certain amount of caution. This holds equally true for the risks as well as the benefits,” says Dr. Kenneth Mukamal, associate professor of medicine at Harvard-affiliated Beth Israel Deaconess Medical Center.

Pot and pain

Some of the strongest evidence supporting the medical use of marijuana is marijuana’s benefits for managing chronic pain. Cannabinoid compounds (see “Cannabis 101”) interact with receptors in nerve cells to slow down pain impulses and ease discomfort. Cannabinoids also have been shown to be effective in quelling nausea and vomiting. In addition, marijuana is a powerful appetite inducer. The combination of these attributes makes marijuana a therapeutic option for people coping with the side effects of chemotherapy and others who are in danger of unintended weight loss. However, in conditions where gaining extra weight might exacerbate existing health problems, such as diabetes, appetite stimulation would be counterproductive.

Cardiovascular effects

One of the few things scientists know for sure about marijuana and cardiovascular health is that people with established heart disease who are under stress develop chest pain more quickly if they have been smoking marijuana than they would have otherwise. This is because of complex effects cannabinoids have on the cardiovascular system, including raising resting heart rate, dilating blood vessels, and making the heart pump harder. Research suggests that the risk of heart attack is several times higher in the hour after smoking marijuana than it would be normally. While this does not pose a significant threat to people who have minimal cardiovascular risk, it should be a red flag for anyone with a history of heart disease. Although the evidence is weaker, there are also links to a higher risk of atrial fibrillation or ischemic stroke immediately following marijuana use. Consistent with these links, studies by Dr. Mukamal and colleagues also suggest that marijuana smoking may increase the long-term death rate among heart attack survivors.

Questions remain on marijuana’s benefits and risks

Most of the evidence linking marijuana to heart attack and stroke is based on reports from people who smoked it. So it’s hard to separate the effects of cannabinoid compounds on the cardiovascular system from the hazards posed by the irritants and carcinogens contained in the smoke. Because cannabis smoke is known to cause airway inflammation, wheezing, and chest tightness, people with lung diseases should not smoke it. Other people who should just say no to marijuana include those who may be vulnerable to developing schizophrenia or addiction.

Cannabis 101

The cannabis plant contains more than 100 unique chemical components classified as cannabinoids. These are the active ingredients that bind to specific receptors in the brain and other parts of the body. The two most prevalent types are tetrahydrocannabinol (THC), which is primarily responsible for the mind-altering properties sought out by recreational users, and cannabidiol (CBD), which has no psychoactive effect. Cannabidiol may actually work to offset the psychoactive properties of THC.

The magnitude of marijuana’s psychoactive effect depends on the THC level in the particular strain of plant, which parts of the plant are used, and the route through which the drug enters the body. Legalization in some states has led to the breeding of strains that are three to seven times more potent than those available three decades ago.

The impact of smoked or inhaled marijuana is generally felt within a few minutes and lasts two to four hours. Marijuana ingested in food or beverages kicks in more slowly and lasts longer.

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Is Marijuana Bad for Your Heart?

A study published today in the Journal of the American Heart Association further demonstrates that marijuana use increases the risk of major cardiovascular events such as heart attack, heart rhythm disorders, and stroke, particularly in young people without other heart disease risk factors. The extreme seriousness of these events is underscored by a death rate exceeding 25 percent in those affected.

We need to pay attention to the heart risks of marijuana because medical marijuana use is on the rise. Since November 5, 1996, when Californians approved Proposition 215, removing state-level criminal penalties on the use, possession, and cultivation of marijuana by patients who “would benefit from medical marijuana,” similar laws have been enacted in 20 U.S. states. Recently, the states of Colorado and Washington took the further step of “legalizing” recreational marijuana use.

This rising tide of marijuana law reform has been enabled by widely held perceptions that marijuana use is harmless and that it is effective in “treating” a variety of medical disorders. The National Organization for the Reform of Marijuana Laws states that marijuana is “nontoxic.” According to a recent NBC News/Wall Street Journal poll, 55 percent of Americans support legislative efforts to legalize marijuana based on these views.

Contrary to these views, however, marijuana has well-known adverse effects on the brain, lungs, and heart.

Marijuana use impairs short-term memory, alters judgment and decision-making, and affects mood – potentially producing severe anxiety, paranoia, and psychosis in extreme cases. Marijuana smoke is an irritant to the lungs, similar to tobacco smoke. Marijuana smokers have the same respiratory problems as tobacco smokers, including an increased risk of lung infections, although no increased risk of lung cancer has been described to date in the medical research.

How Marijuana Affects Cardiovascular Health

Marijuana use raises the heart rate by as much as 100 percent – most acutely after smoking, but this effect may last for a few hours. Other effects of marijuana use on the heart include:

  • Chest pain
  • Heart attack
  • Heart arrhythmias (or irregular heartbeats)
  • Weakening of the heart (called cardiomyopathy)

A prior study showed a 480 percent increase in the risk of heart attack within the first hour following marijuana use, primarily in those at risk for heart attack. Other cardiovascular effects of marijuana use include reversible strokes, called transient ischemic attacks, and permanent strokes, as well as abnormalities of peripheral artery function that can lead to constriction of blood vessels, ischemic ulcers (ulcers on the legs and feet), and death of tissues in the fingers or toes.

The new marijuana-heart risk study from Emilie Jouanjus, MD, and colleagues provides some of the best evidence to date of the potentially deadly cardiovascular consequences of marijuana use. The investigators analyzed serious cardiovascular events following marijuana use that were reported to the French Addictovigilance Network between 2006 and 2010. Of the 1,979 marijuana-related health problems reported, 35 (or about 2 percent) were cardiovascular events. These included 20 heart attacks, 10 peripheral artery problems, 3 cerebral events (including temporary cortical blindness), and 2 heart rhythm abnormalities. The average age of patients with cardiovascular events was about 34, and most patients had few or no risk factors for cardiovascular disease. Shockingly, 25 percent of these 35 patients died as a consequence of their cardiovascular event.

While these numbers may seem small, marijuana-related health problems are likely to be underreported, and the numbers could possibly be much larger. Assuming that the numbers are not underreported and applying these observations to the estimated 14 million Americans who regularly use marijuana, these French findings could translate into about 1,000 cardiovascular events per year in the United States alone. More study is needed to confirm these findings and estimates.

In the meantime, as with any medicinal or recreational drug, consider risks as well as benefits. This French study should be taken into account. Dying from a marijuana-induced heart attack could be a real bummer.

Is Smoking Weed as Bad for Your Heart as Cigarettes?


In a new report researchers at Brigham and Women’s Hospital estimate nearly two million U.S. adults who have heart disease report using marijuana.

By Tessa Yannone· 1/20/2020, 4:40 p.m.

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Here’s something to be blunt about: A new study has found that using pot carries many of the same hazards for heart health as smoking tobacco.

In a report released today in The Journal of the American College of Cardiology, a team of researchers at Brigham and Women’s Hospital found that nearly two million U.S. adults with heart disease reported using marijuana at some point in their life. The data for the study was gathered from responses to the Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey between 2005-2016. Participants in the survey were asked if they ever used marijuana or hashish, a drug made from the resin of the cannabis plant, and if they had ever been diagnosed with heart disease including heart failure, congestive heart failure, coronary heart disease, or heart attack.

The report underscores how we’re entering new territory in understanding the health impacts of marijuana use. “For the first time more people are using marijuana as opposed to smoking cigarettes,” says Dr. Muthiah Vaduganatham, a cardiologist at the Brigham and one of the researchers behind the report. “Because of this we, as a community, need to focus our attention to identifying strategies to promote its safe use.” But because marijuana is classified as a schedule I drug by the U.S. Drug Enforcement Agency, its research is highly restricted and it is illegal to conduct rigorous controlled trials of marijuana products in the United States.

The researchers found that many of the same toxic chemicals released by cigarettes are also found in marijuana smoke. Inhaling cannabis may increase heart rate and blood pressure causing a heart attack, and those using marijuana are more likely to experience abnormal heart rhythms and stroke. While it’s pretty obvious that inhaling anything into the lungs besides good ‘ole oxygen is less than ideal, Vaduganatham points out marijuana use—in any of its forms—affects the heart by issuing changes to things like sympathetic tone and blood pressure. He also points out how marijuana can disrupt the efficacy of cardiovascular medications.

The findings, however, don’t mean we should stop using medical marijuana. Since cannabis is used for a wide range of medical treatments—from managing conditions such as epilepsy to easing pain during cancer treatments—Vaduganatham says health care decisions should be made on a case-by-case basis that weigh the risks of any drug against its benefits.

More than anything else, the report is a call for more research. Although clinical trials of marijuana are illegal, Vaduganatham says that more studies involving a large amount of data, like this one, are possible and encouraged. The researchers also urge clinicians to ask their patients about marijuana use and to keep the dialogue open. Either way you light it, maybe you should think twice next time before you puff, puff, pass—or maybe you already have—and in that case, this is just a friendly reminder.

There is a lot of controversy about marijuana as it increasingly becomes legal to use. As of now, 22 states and the District of Columbia have established medical cannabis programs and Colorado and Washington State have legalized recreational use, with Oregon soon to follow.

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Most people know about the dangers of tobacco use but may think that marijuana is beneficial or benign at worst. It may help patients with nausea that resists treatment and could ease the side effects of chemotherapy.

However, it’s hard to justify using marijuana for anyone with cardiovascular disease because there just isn’t enough information available to know how it will affect their hearts. The drug’s effect on cardiovascular health is simply uncharted territory. These patients should steer clear of the drug until they talk with their doctor.

Here are four reasons to avoid, or at least be cautious, if you’re a heart patient:

  1. Scientific data is scarce. There aren’t definitive, rigorous scientific studies to guide us about marijuana use because the drug was illegal for many decades, says Steven Nissen, MD, Chairman of Cleveland Clinic’s Department of Cardiovascular Medicine.“Few, if any high-quality studies have been performed, and that leaves a knowledge gap,” he says.Any drug or treatment that has not been thoroughly studied can pose a danger. For example, legal but unregulated supplements, such as ephedra and licorice root, can have dangerous side effects on your heart’s function.

    Anesthesiologist Steven Insler, DO, urges caution. “With an impaired heart and considerable risk factors, I would caution against the use of marijuana in any form,” he says.

  2. We don’t know what it will do to your heart. There are several documented studies that show that marijuana use is associated with increased heart rate and fluctuations in blood pressure, which may be implicated in developing heart attacks or strokes.More recently, a study in Journal of the American Heart Association reported that there are potential cardiovascular dangers to young adults using marijuana.While research is still limited, what we do know appears to show a damaging effect on the cardiovascular system, Dr. Insler says.

    “We need more studies to understand how marijuana affects people and their hearts, but with what we know so far, I believe it would be imprudent to recommend marijuana use to those with cardiovascular risk factors,” he says.

  3. We don’t know what it will do to your lungs and blood vessels. Apart from the effects that marijuana use has on the body, the delivery method for the drug raises other concerns.Smoking marijuana can harm lung tissues and cause scarring and damage to small blood vessels. It can also lead to increased risk for mini-stroke — a danger for anyone, but of particular risk for patients with existing heart and circulatory problems.As an alternative, people might consider eating marijuana in foods such as cookies or brownies, but this also poses a risk because there is no reliable way to prescribe proper dosing or portion size. Increasing genetic manipulation of marijuana types and strains further muddies this picture. The effects are unpredictable.
  4. We don’t know what it will do to your brain. Ongoing studies have found links between marijuana and mental health problems, including bipolar disease. Marijuana use also has links to depression, physical inactivity and social isolation, all factors that worsen outcomes for heart patients.“Marijuana may at least be a component cause of psychosis,”Dr. Insler says. At least three meta-analyses (1, 2 and 3) suggest this. Further, this association appears to be related to the dose, meaning that more frequent or heavier users face an increased risk.

What we do know: Caution is warranted

The active ingredient in marijuana is THC (tetrahydrocannabinol), and many tissues in your body have THC receptors. That means marijuana can have some effect on virtually every organ, and that effect is also virtually unknown. Unlike FDA-approved medications, marijuana has no established dosage, safety or efficacy studies.

“We have limited knowledge about the potential benefit of marijuana, but given the information about potential negative side effects, its use as part of an overall treatment plan for a specific disease should be done under a doctor’s supervision,” Dr. Insler says.

Working with your doctor, frequent assessments of your heart function, including heart rate, blood pressure and rhythm are needed.

Doctors urge more study on how medical or recreational marijuana impacts heart function as its use continues to make gains in public acceptance.

Marijuana may be risky for those with heart disease

Although marijuana may have some benefits, its use could cause health issues for older people with cardiovascular disease. One case, in particular, is sparking some questions.

Share on PinterestMarijuana in edible form may have cardiovascular risks for people at risk.

In recent years, the legalization of marijuana has become more widespread.

Some people use the drug recreationally, while some use it to relieve chronic pain and the impact of some mental health issues.

However, experts state that there needs to be more research into the effects of marijuana in older people.

Specifically, the scientific community needs to focus on educating the public on aspects such as potential effects and recommended dosages.

A Canadian Journal of Cardiology case report goes some way toward that. It examined a 70-year-old man who had a heart attack after eating a lollipop that was infused with 90 milligrams (mg) of tetrahydrocannabinol (THC) — which is largely responsible for marijuana’s psychological effects.

The man lived with stable coronary artery disease, and he was taking cardiac medication. He ate most of the lollipop and did so to help minimize pain and improve sleep.

Dr. Alexandra Saunders — who works in Horizon Health Network’s Department of Cardiology in New Brunswick, Canada — described the man’s 90-mg dose as “inappropriate.”

Smoking a typical joint would expose a person to just 7 mg of THC, while a starting dose of a synthetic THC called dronabinol is only 2.5 mg. People with AIDS or cancer tend to use this version, and it can also combat nausea and encourage appetite.

“Marijuana can be a useful tool for many patients, especially for pain and nausea relief. At the same time, like all other medications, it does carry risk and side effects.”

Dr. Alexandra Saunders

A cardiovascular link

The large amount of THC the man consumed caused him to experience anxiety and hallucinations. The strain that these effects put on his body is what likely caused his heart attack, by triggering a response in the sympathetic nervous sytem.

His cardiac event was demonstrated by a rapid heart rate, an abnormally high blood pressure, and the release of the stress hormone catecholamine. The man’s chest pain went away as soon as the effects of the marijuana had worn off.

Previously, there had been reports of similar incidences showing a relationship between cannabis consumption and acute cardiovascular adverse events. These have ranged from an irregular heartbeat to stroke, and even sudden death.

However, Dr. Robert S. Stevenson — who also works at Horizon Health Network’s Department of Cardiology — says, “Most previous research on marijuana-induced myocardial ischemia focused mostly on younger patients and did not focus on its different formulations and potencies.”

A word of warning

The doctors examining the most recent case have issued advice, particularly for older people who use marijuana.

They advise people to use the smallest dose possible for their chosen benefit. Anyone who has a cardiovascular condition or is at high risk of developing one should steer clear of THC. Instead, they can try cannabidiol, which is a nonpsychoactive alternative.

They should also take factors such as tolerance and consumption method into consideration. For example, a person who has smoked marijuana over a long period of time is likely to experience fewer distressing side effects than someone who is not used to the drug.

Similarly, eating a THC-infused brownie or lollipop would expose a person to more THC than if they had used a vaporizer.

With further decriminalization, it is hoped that scientists will work on conducting more research into the potential side effects of marijuana. For now, educating the public — especially aging members — should be a priority.

“For better or worse,” concludes Dr. Neal L. Benowitz, chief of the Division of Clinical Pharmacology and Experimental Therapeutics at the University of California, “providing advice and care to such patients who are using cannabis is now necessary for the provision of optimal medical care to these patients.”


Within a few minutes after inhaling marijuana smoke, a person’s heart rate speeds up, the breathing passages relax and become enlarged, and blood vessels in the eyes expand, making the eyes look bloodshot. The heart rate—normally 70 to 80 beats per minute—may increase by 20 to 50 beats per minute or may even double in some cases. Taking other drugs with marijuana can amplify this effect.

Limited evidence suggests that a person’s risk of heart attack during the first hour after smoking marijuana is nearly five times his or her usual risk.73 This observation could be partly explained by marijuana raising blood pressure (in some cases) and heart rate and reducing the blood’s capacity to carry oxygen.74 Marijuana may also cause orthostatic hypotension (head rush or dizziness on standing up), possibly raising danger from fainting and falls. Tolerance to some cardiovascular effects often develops with repeated exposure.75 These health effects need to be examined more closely, particularly given the increasing use of “medical marijuana” by people with health issues and older adults who may have increased baseline vulnerability due to age-related cardiovascular risk factors (see “Is marijuana safe and effective as medicine?”).

A few studies have shown a clear link between marijuana use in adolescence and increased risk for an aggressive form of testicular cancer (nonseminomatous testicular germ cell tumor) that predominantly strikes young adult males.76,77 The early onset of testicular cancers compared to lung and most other cancers indicates that, whatever the nature of marijuana’s contribution, it may accumulate over just a few years of use.

Studies have shown that in rare cases, chronic use of marijuana can lead to Cannabinoid Hyperemesis Syndrome—a condition marked by recurrent bouts of severe nausea, vomiting, and dehydration. This syndrome has been found to occur in persons under 50 years of age and with a long history of marijuana use. Cannabinoid Hyperemesis Syndrome can lead sufferers to make frequent trips to the emergency room, but may be resolved when a person stops using marijuana.78

MONDAY, Jan. 22, 2018 (HealthDay News) — Anyone worried that smoking a lot of pot could lead to a heart attack or stroke will just have to keep worrying for the time being.

There’s not enough scientific evidence to say one way or the other how marijuana affects heart health, a new review has concluded.

“Our review found insufficient evidence to draw meaningful conclusions that marijuana use is associated with cardiovascular risk factors and outcomes,” said lead study author Dr. Divya Ravi, an internist with the Wright Center for Graduate Medical Education in Scranton, Pa.

For their review, Ravi and her colleagues pored through medical literature and found 24 studies that evaluated marijuana use and its effects on either heart health risk factors or actual health problems such as heart attack or stroke.

A few studies showed that pot use might benefit the heart, but these were contradicted by other studies that reported potential harmful effects, Ravi said.

For example, some studies linked marijuana use to less diabetes, lower blood sugar and higher levels of “good” HDL cholesterol, the researchers found. And despite anecdotal reports of marijuana bringing on the “munchies,” no studies have tied pot use to weight gain or obesity.

However, other studies found that smoking pot was associated with a greater risk for heart attack and death from heart disease.

“The evidence is insufficient to draw any conclusions,” Ravi said. “The association between marijuana and cardiovascular health has not been adequately studied to date.”

Two heart experts not involved with the study said they’re not surprised by the lack of evidence, given how difficult it is to conduct studies on marijuana use.

Results could become more definitive in the future, thanks to some states legalizing marijuana. That might make people more comfortable discussing their pot use with researchers, said Dr. Russell Luepker, a professor with the University of Minnesota’s School of Public Health.

The vast majority of states allow limited use of medical marijuana under certain circumstances. And eight states and Washington D.C. have legalized recreational pot use.

As marijuana legalization spreads across the U.S., questions about the drug’s effects on public health become more relevant. But in at least one area — heart health — there’s just not enough scientific evidence to reach firm conclusions about the effects of regular marijuana use, a new review suggests.

After reviewing two dozen studies that weighed the benefits and risks of marijuana use in adults, the researchers determined that there was too little information to evaluate the drug’s effects on the development of heart-related problems as well as risk factors for heart disease, according to the findings, which were published Jan. 22 in the journal Annals of Internal Medicine.

“The review found insufficient evidence to draw meaningful conclusions that marijuana use is associated with cardiovascular risk factors and outcomes,” said lead author Dr. Divya Ravi, a resident in internal medicine at the Wright Center for Graduate Medical Education in Scranton, Pennsylvania.

A few studies have suggested that marijuana use has positive effects on heart health; however, these studies were cross-sectional, meaning they collected data at a single point in time, Ravi said. But more-robust long-term studies have contradicted such findings of marijuana’s possible benefits, reporting potential harmful effects for the drug, she noted.

This isn’t the first analysis to suggest that scientists aren’t sure how marijuana use affects heart health. A large report published in 2017 from the National Academies of Sciences, Engineering and Medicine reviewed the health effects of marijuana and concluded that “more research is needed to determine whether and how cannabis use is associated with heart attack, stroke and diabetes.” That report also found some evidence to suggest that smoking pot may trigger a heart attack.

In the new review, researchers looked at data collected from 13 studies on marijuana use and the drug’s effects on various risk factors for heart disease, including obesity, high blood pressure and levels of fat in the blood. The researchers also analyzed data from 11 studies investigating the link between marijuana use and heart-disease outcomes, such as stroke, heart attacks and deaths from heart-related causes.

The studies’ participants ranged in age from 18 to 84, and they may have smoked marijuana, consumed it as an edible or used the drug as a pharmaceutical treatment.

Challenges of researching marijuana

The analysis found that there was not enough evidence that a person’s marijuana use either increases or decreases most risk factors for heart disease. And the researchers also concluded there was a lack of information on the link between pot use and negative cardiovascular outcomes.

For example, although smoking pot is believed to trigger an increase in appetite, the researchers found no evidence that marijuana use is associated with weight gain or obesity.

Some problems with the reviewed studies were that many of the participants were younger, and heart disease and stroke typically occur in middle-age and older people, the researchers said. In addition, researchers in the reviewed studies often relied on people’s memories, asking them to recall their marijuana use, which can be unreliable. And participants may have used different varieties and strengths of the drug, which could complicate comparisons.

Designing studies to understand the health effects of marijuana can be complicated: Marijuana has been an illegal substance, and therefore, researching it has been challenging, Ravi told Live Science. One reason for the difficulty is that conducting observational studies involves asking people about the frequency and intensity of their drug use, she said. In the past, study participants may have felt uncomfortable disclosing their use of an illegal substance to researchers, Ravi said.

She also noted that researchers have to follow large groups of marijuana users and nonusers for long periods of time to observe the effects of daily use on heart health.

At this point, there’s too little data on the potential harms or benefits of regular marijuana use for doctors to advise people about the drug’s effects on heart health, Ravi said.

Originally published on Live Science.

Study Estimates 2 Million People With Heart Disease Have Used Marijuana

Marijuana use is on the rise as more states legalize it for medicinal and recreational purposes, and physicians are fielding more questions about its safety.

Although smoking tobacco is responsible for approximately one in four deaths from cardiovascular disease, the effects of smoking marijuana on the heart are not fully understood. Some studies suggest that marijuana can trigger heart attacks and strokes in some users.

Ersilia DeFilippis, MD, a second-year cardiology fellow at Columbia University Irving Medical Center and NewYork-Presbyterian, first became interested in marijuana’s effect on the heart a few years ago when studying heart attacks in people under 50. “We noted that 10% of patients in a registry of young heart attack patients had used marijuana and/or cocaine,” she says.

DeFilippis and colleagues recently reviewed the medical literature to find out what’s known about marijuana’s effect on the heart and what’s still unknown. Their full report was published Jan. 20 in the Journal of the American College of Cardiology.

Here are five highlights from the review:

2 Million People with Heart Disease Have Used Marijuana

Marijuana is the most commonly used drug of abuse. It’s estimated that approximately 90 million American adults have used the drug at least once in their life, and more than 39 million have used the drug in the past year.

Based on responses to the National Health and Nutrition Examination Survey from 2016, DeFilippis and her colleagues estimate that about 2 million adults in the United States who have cardiovascular disease currently use marijuana or have used the drug in the past.

“In addition to the 2 million marijuana users with diagnosed cardiovascular disease, many more may be at risk,” DeFilippis says. “With many adolescents and young adults turning to marijuana, it is important to understand the cardiovascular implications they may face years down the line.”

Marijuana’s Potency Today Is Higher

The potency of marijuana—the percentage of THC contained in the plant—has steadily increased over the past 30 years, from about 4% in the mid-1990s to 12% in 2014. However, most scientific studies of cannabis tested products with THC levels between 1.5% and 4%.

“Higher potency may translate into greater effects on the conduction system, the vasculature, and the muscle of the heart,” DeFilippis says. “It also highlights the need for real-world data given the variety of marijuana products and formulations available for purchase.”

THC is the most psychoactive chemical in marijuana, but marijuana also contains more than 100 compounds, called cannabinoids, that are chemically related to THC.

Receptors for cannabinoids are highly concentrated in the nervous system but also can be found in blood cells, muscle cells, and other tissues and organs.

Cannabinoids Can Interact with Drugs Used to Treat Heart Disease

Cannabinoids inhibit certain enzymes in the body, which affects the metabolism of many drugs for heart disease, including antiarrhythmics, statins, calcium-channel blockers, beta blockers, and warfarin.

Researchers believe that cannabinoids may increase the activity of these prescribed drugs in the body, though limited data are available to guide physicians in adjusting dose to compensate for marijuana use.

Marijuana May Be Linked to Heart Attacks and Strokes

Studies have identified marijuana smoking as a potential trigger of heart attacks, and marijuana use is not infrequently detected in adults who have experienced heart attacks at an early age (under 50).

A small experimental study found that smoking marijuana can bring on angina (chest pain) more quickly in patients with coronary heart disease compared with smoking a placebo.

Though current evidence for a link between marijuana and heart attacks is modest, it’s thought that smoking marijuana may increase cellular stress and inflammation, which are known to be precipitating factors for coronary artery disease and heart attacks.

Cerebrovascular events, including strokes, also have been associated with marijuana use. It’s thought that marijuana may induce changes in the inner lining of blood vessels or alter blood flow.

Physicians Should Screen for Marijuana Use

“Although we need more data, the evidence we do have indicates that marijuana use has been associated with coronary artery disease, arrhythmia, cardiomyopathy, and more,” DeFilippis says.

“Therefore, asking patients about marijuana use may help in risk assessment. In addition, we know that marijuana use affects the metabolism of many common cardiac drugs. In order to make sure patients are getting therapeutic doses without untoward side effects, it is important for cardiologists to talk to their patients about marijuana use.”

Marijuana and Your Heart

Legalized marijuana is now a reality in Canada. This opening up of legal access will have a variety of health implications. In addition, marijuana is increasingly prescribed for much of what ails us, from the pain and inflammation of osteoarthritis to a host of other conditions, many of which affect seniors – the same people who are at greatest risk of heart disease. What the legal use of marijuana could mean for your heart, whether you’ve already had a cardiac event or are at risk of having one, is in many ways an open question.

Physician and researcher Andrew Pipe, MD, and behavioural scientist Robert Reid, PhD, both of the Ottawa Heart Institute’s Division of Prevention and Rehabilitation, are widely published experts in the prevention of heart disease. As Dr. Pipe put it, “When we consider marijuana and issues relating to the heart we really are steering into terra incognita.”

The long-standing illegal status of marijuana has made it a lower priority for health researchers and posed a hurdle to conducting studies. What we do know about the drug’s effects on the cardiovascular system is not a lot, said both men.

“We’ll see an increased interest in research as a result of the liberalized approach to marijuana,” added Dr. Reid, Deputy Chief of the Division.

Watch Dr. Andrew Pipe discuss marijuana and the heart with CTV Ottawa Morning Live’s Henry Burris.

What the Research Tells Us

A 2014 review article in the New England Journal of Medicine summarized what is known about the effects of marijuana on all aspects of health. The authors found that marijuana use has been associated with vascular conditions that increase the risk of heart attack and stroke, although the mechanisms by which that happens aren’t clear. The article also noted that the risk is mainly associated with immediate use of marijuana and isn’t necessarily cumulative.

Physician and researcher Andrew Pipe, MD

There is some epidemiological evidence that marijuana use in young men, in particular, is associated with an increased risk of heart attack within an hour of use, said Dr. Reid, whereas the risk in young women is not increased to the same degree.

Another article, from 2013 in the American Heart Journal, found that habitual marijuana use before a heart attack was associated with a higher mortality rate over the next 18 years, although the difference wasn’t statistically significant.

Both Drs. Pipe and Reid expect increased interest in research around marijuana use. They also both said that, based on what evidence there is, as well as common sense, trying this newly legal drug should be approached with caution and that, if you must, then don’t smoke it.

Physiological Effects of Smoking Marijuana

When you smoke marijuana, your heart rate and blood pressure increase. At the same time, smoking in general, whether tobacco, marijuana or a mixture of the two, reduces the capacity of the blood to deliver oxygen throughout the body – an effect of the products of combustion such as carbon monoxide. This combination adds up to increased risk for a cardiac event like a heart attack, particularly while a person is smoking and immediately afterward.

“There is a strong case for saying no one should ever smoke marijuana because of the products of combustion,” said Dr. Pipe. “We can say with absolute certainty that smoking marijuana will harm the ability to deliver oxygen, and that’s not good.”

While Dr. Reid pointed out that the relationship between marijuana use and heart disease remains, at this point, “largely theoretical,” there is existing evidence that marijuana use may lead to quicker onset of exercise-induced angina during a stress test among people with heart disease. This suggests another reason why it is not a good idea to use marijuana, he noted. He also noted that marijuana use could be problematic for people with an irregular heartbeat, or arrhythmia, because it activates the sympathetic nervous system.

What Happens to Your Heart When You Use Marijuana?

  • Your heart rate and blood pressure increase, forcing your heart to work harder.
  • If you smoke the marijuana, the capacity of your blood to transport oxygen throughout your body, including to your heart, is reduced.
  • The result is strain on your heart and a reduced ability to handle increased demands.

The Problem with Assessing Impact

In theory, it shouldn’t be that difficult to assess the impact of marijuana use. In reality, though, it’s actually difficult to untangle.

For one thing, marijuana is rarely used in isolation. Generally, tobacco, alcohol or both are involved. And while the amount smoked is less with marijuana, experience has shown that smoking marijuana can make it harder to quit smoking tobacco. In reality, most people use the two together, thus, as Dr. Reid punned, “clouding the issue.”

Behavioural scientist Robert Reid, PhD

“Significant numbers of individuals who smoke lots of marijuana daily come to us because they want to stop smoking,” said Dr. Pipe. “But for heavy marijuana smokers mixing it with tobacco, the likelihood of quitting is much less.”

Another problem relates to dose control. There are no standards for the production of marijuana and the amount of THC (the ingredient that gives marijuana its “high”) it contains. The problem becomes more acute when marijuana is eaten, said Dr. Pipe. People who eat marijuana may not feel the effect as quickly as those who smoke it, leading them to use more.

Marijuana and Depression

One concern frequently raised is the link between marijuana and depression. Depression is a known risk factor for heart disease, in part because it interferes with a patient’s ability to adopt healthier behaviours, and many believe that marijuana use can lead to depression.

But it’s a chicken-and-egg kind of argument. We really don’t know whether marijuana causes depression, said Dr. Pipe, or whether people who are depressed use marijuana at least in part as an effort to self-medicate. Either way, it underscores yet another area where more research is needed.

Edible Marijuana

Eating marijuana is an option to avoid the toxins associated with smoking it, but other risks are likely similar.

“Edible forms would be different in terms of impacts on the oxygen carrying capacity of blood,” said Dr. Reid, “But there would still be some in terms of heart rate and blood pressure.”

This is also a rich area for future research, said Dr. Pipe, particularly isolating and purifying the chemical compounds in marijuana that have a therapeutic effect while eliminating the psychoactive ingredients.

“We don’t advise people in pain to chew willow bark , we tell them to take Aspirin,” he said. “There’s no reason marijuana should be any different.”

What’s a Patient to Do?

With all this uncertainty, it’s hard to know the wisest course for a patient. Dr. Reid advised that patients “start asking” their care providers about using marijuana just as they would about alcohol and to use caution, until something more definitive is known.

“ probably wouldn’t be a good idea for someone with ischemic heart disease,” said Dr. Reid, because of the reduced oxygen transport through the body. “There’s no reason to begin marijuana use, and there could be more risk associated with it.”

“Don’t smoke it!” added Dr. Pipe. “Have a careful, considered conversation with the physician who is responsible for your care.”

“I’m pretty confident saying if you don’t use it now, there’s no reason to start,” concluded Dr. Reid.

A previous version of this article was originally published in July 2017.

Ignore Kevin Smith: Weed Won’t Save Your Life During a Heart Attack

“It’s nice that the physician allegedly said that the joint helped Smith, but that’s just not supported by evidence. Furthermore, the idea that ‘calming down’ would be relevant is a bit of a stretch,” he said. “Clearly, panicking or running around, which might elevate someone’s heart rate, is not good in the setting of a heart attack. However, heart attacks are not caused by emotional stress and are not directly influenced by one’s attitude.”

What to do if you’re worried about a heart attack

Lighting up a joint isn’t a good idea if you experience any signs of a heart attack such as chest pain, shortness of breath, and discomfort in the upper body.

Instead, take four baby aspirin or one full-sized aspirin and get to the hospital, where doctors have drugs on hand to treat the issue and calm you down, said Nguyen.

“In the emergency room, we give patients morphine mainly to relieve pain, but also to lower the heart rate and keep them relaxed,” he said.

According to Tishler, people who are already undergoing treatment for cardiovascular issues should avoid ingesting cannabidiol (CBD), a non-intoxicating compound found in the cannabis plant.

“CBD, which is increasingly popular, can interact with the blood thinners that many heart patients are on. This, particularly in the case of Plavix in patients who have recently had a coronary stent placed, is a more significant potential threat,” he said.

Heart disease is the leading cause of death in America, according to the Centers for Disease Control and Prevention. About 735,000 Americans have a heart attack each year.

Since his heart attack a few months ago, Smith has made lifestyle changes to improve his health. He has reportedly dropped more than 30 pounds and referred to his heart attack as “the greatest thing that ever happened.”

He also said his doctors have cleared him to continue using marijuana.

New Study Suggests Marijuana Use Does Not Increase Risk of Heart Arrhythmias, Instead May Reduce Risk of AFib

According to new research, smoking marijuana may not be associated with an increased risk of ventricular fibrillation (VF) and ventricular tachycardia (VT) following an acute myocardial infarction (AMI), or heart attack. The study also reported that marijuana users had a decreased risk of atrial fibrillation (AFib) and in-hospital mortality. The results are scheduled to be presented on Thursday, May 10 at Heart Rhythm 2018, the Heart Rhythm Society’s 39th Annual Scientific Sessions.

2018 Press Release

Presented at Heart Rhythm 2018, first ever in-human study of more than one million patients assesses arrhythmic effects of marijuana after a heart attack

According to new research, smoking marijuana may not be associated with an increased risk of ventricular fibrillation (VF) and ventricular tachycardia (VT) following an acute myocardial infarction (AMI), or heart attack. The study also reported that marijuana users had a decreased risk of atrial fibrillation (AFib) and in-hospital mortality. The results are scheduled to be presented on Thursday, May 10 at Heart Rhythm 2018, the Heart Rhythm Society’s 39th Annual Scientific Sessions.

Recent federal data reported a stunning 455 percent increase in marijuana consumption among U.S. adults ages 55-64 years and 333 percent in ages over 64 years between 2002 and 2014. In fact, one in eight Americans say they smoke marijuana. While results of previous studies show links between cannabis use and increases in heart rate and blood pressure, little is known about the cardiac-related effects for heart arrhythmias including VF and VT. VTis a very fast but regular heart rhythm that can lead to VF, which is fast and irregular and can cause sudden cardiac arrest.

The study compared clinical profiles and in-hospital outcomes between reported marijuana users vs. non-users from 1994 to 2013. The primary endpoint was VT/VF or cardiac arrest and the secondary endpoint was atrial fibrillation or mortality. The patient group included people between the ages of 18-70 years with a primary diagnosis of AMI (ICD-9-CM code 410.xx) from eight states including California, New York, New Jersey, Vermont, New Hampshire, Colorado, Texas, and West Virginia. Patients who used cocaine, methamphetamine or alcohol were excluded from the study. Variables included in a step-forward multivariate logistic regression model included age, race and cardiac risk factors.

In total, 3,854 of 1,273,897 patients admitted with AMI reported marijuana use. Findings from the study show marijuana users tended to be younger, male and less likely to have coronary artery disease (CAD) or coronary risk factors than non-users. Primary endpoints show that 9.7 percent (n=374) marijuana users and 9.7 percent (n=122,797) non-users experienced VT/VF or cardiac arrest. Secondary endpoints show that 4.5 percent (n=173) marijuana users vs. 8.7 percent (n=110,153) non-users had AFib, and 4 percent (n=135) vs. 6 percent (n=75,311) died, respectively. Despite there being no difference in the risk for VT/VF, researchers found in-hospital mortality was lower in marijuana users and a trend toward decreased risk of AFib was lower in marijuana users.

“The legalization of marijuana is spreading quickly across the U.S. resulting in more people using it, but we still don’t know the true, long-term impact it has on one’s heart health. Our study is the first to examine the relationship between marijuana use after a heart attack and various arrhythmias and we did not see a negative connection,” said senior author Christine Tompkins, MD, assistant professor of cardiology medicine at University of Colorado School of Medicine. “We are just one step closer to a better understanding of the various heart effects of marijuana, so that we are able to take the necessary actions to provide optimal patient care.”

The authors have noted that future studies are warranted to further understand the temporal relationship of marijuana and arrhythmias in patients with chronic ischemic heart disease, and are actively involved in a prospective observational study. They have also expressed interest in understanding the effects of marijuana in other chronic cardiac conditions, such as congestive heart failure and hypertension. The authors emphasize a need to understand how marijuana affects the heart so as to provide patients with informed choices, particularly since use in adults over the age of 50 years is increasing exponentially.

Sessions details:
“Poster Session II: Arrhythmic Effects of Marijuana Following Acute Myocardial Infarction”

Heart Rhythm 2018 is the most comprehensive educational program for heart rhythm professionals, featuring more than 200 educational sessions and more than 140 exhibitors showcasing innovative products and services. The Heart Rhythm Society’s Annual Scientific Sessions have become the must-attend event of the year, allowing the exchange of new vital ideas and information among colleagues from every corner of the globe. For more information, visit

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