How Cannabis May Affect Your Heart Health
Share on Pinterest Researchers are learning how THC in cannabis may affect the heart.
- THC is the main mind-altering (psychoactive) ingredient in cannabis, or marijuana, that can cause a person to feel high.
- THC-containing products stimulate the heart as well as promote vascular inflammation and oxidative stress.
- This may lead to elevated blood pressure, abnormal heart rhythms, and overall higher risk of heart attack, stroke, and sudden death.
Cannabis may have medicinal properties, but it could also be harmful to the heart and blood vessels, according to a report from the American Heart Association (AHA).
The AHA’s statement in the journal Circulation looked at several studies on the topic, as cannabis use has increased over the past decade.
Cannabis, also known as marijuana, refers to the varieties of cannabis plants that contain tetrahydrocannabinol (THC).
THC is the main mind-altering (psychoactive) ingredient in cannabis that can cause a person to feel high. Cannabinoids are compounds in cannabis. Cannabidoil or CBD is a commonly known cannabinoid said to have some health benefits. CBD is different from THC.
Researchers have had a tough time trying to study cannabis, as it is listed by the U.S. Controlled Substances Act as a Schedule 1 controlled substance. By definition that means it does not have a medical use and is likely to be misused. In the report, the AHA encouraged the federal Drug Enforcement Administration to remove it from the designation.
Chemicals in cannabis have been linked to higher risk for heart attack, heart failure, and atrial fibrillation. But those studies are observational and did not prove that the chemicals were the cause for the increased risk.
One study cited in the AHA statement reported that 6 percent of patients under the age of 50 who had a heart attack used cannabis. It was linked to having worse all-cause and cardiovascular mortality. Another study noted a significantly higher chance of having a stroke in cannabis users ages 18 to 44, with even greater odds in those who consumed it more frequently compared to those who did not use cannabis.
Dr. Chip Lavie, a cardiologist at the Ochsner Medical Center in New Orleans, Louisiana, said it’s already known that cannabis can have adverse effects on coagulation, increase acute cardiovascular events, and lead to poor vascular effects.
“We still do not have a feel on the impact on occasional users, high dose users, and very chronic users,” Lavie told Healthline.
When cannabis is used on a short-term basis in some patients, the benefits may outweigh the risks. Additional dangers with impure products and vaping still exist, though, he noted.
Dr. Muthiah Vaduganathan, a cardiologist at Brigham and Women’s Hospital in Boston, Massachusetts, pointed out that certain forms of cannabis delivery, such as vaping, can have unique cardiovascular health implications.
Because cannabinoid receptors are distributed all over the body, including in the heart, there’s a potential impact for effects on the heart, Vaduganathan said.
Not all the research on cannabis shows harm, the AHA report stated.
THC-containing products stimulate the heart as well as promote vascular inflammation and oxidative stress. This may lead to elevated blood pressure, abnormal heart rhythms, and overall higher risk of heart attack, stroke, and sudden death, explained Dr. Michael Miller, a cardiology professor at University of Maryland School of Medicine.
If THC concentrations are too high, or taken in a short amount of time, there’s the potential for it to create adverse reactions such as in older people on existing medications.
In contrast, CBD-containing products reduce inflammation and emotional stress that in turn, may serve to reduce the risk heart disease.
“I was not aware of the potential opposing effects between THC in the promotion of heart disease as compared to CBD which may protect against its development and progression,” Miller noted.
Although cannabis can be an effective treatment for medical purposes such as seizure control, or reducing nausea and improving appetite in people with cancer or HIV, some people aren’t aware of its potential harms when used for recreational or nonproven purposes, Miller said.
Miller hopes to see a well-designed clinical trial to determine whether daily use of CBD reduces the risk of a heart attack, stroke, or cardiovascular death.
Experts cite a lack of robust data in specifying the harms and benefits of cannabis on the cardiovascular system. Due to rising concentrations of THC in cannabis, earlier studies may only reflect the impacts of lower levels of THC on people, the AHA report stated.
Most cannabis studies are observational and don’t take into account that some cannabis users also smoke cigarettes, Miller added.
“I would love to know whether, and to what extent, THC may be harmful to the heart in the absence of major risk factors such as cigarette smoking,” he added.
Dr. Stephen Sidney, a senior research scientist with the Kaiser Permanente Northern California Division of Research in Oakland, California, said more research is urgent, as more people 65 and older are using cannabis — and they are at the highest risk for heart attack.
“Most of what we know about the cardiovascular effects of marijuana comes from studies of smoked marijuana. Much more research needs to done on other forms of marijuana, such as edibles, tinctures, and topic preparations,” Sidney told Healthline. “We also need to study how marijuana vaping affects the heart and lungs, because this has overtaken smoking of marijuana cigarettes as the most common use by teens.”
Patients and doctors need to be open about cannabis use and implications, Vaduganathan said.
“While cardiologists often ask and counsel patients about tobacco use, they infrequently screen for cannabis use. Patients similarly may not recognize that cannabis can have important effects on blood pressure, cardiovascular drug metabolism, and overall heart health — some of these may actually be very similar to the adverse health effects of tobacco smoking,” Vaduganathan said.
Marijuana may have medicinal properties, but it could also be harmful to the heart and blood vessels, according to a report from the American Heart Association (AHA).
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.
Image: © UrosPoteko/Thinkstock
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.
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.
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.
Share this page:
- Share this page to Facebook
- Share this page to Twitter
- Share this page to Google Plus
- Email this page
Print this page:
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
More than half of the states in the United States have approved medical marijuana programs. Although the cannabis plant has been used for thousands of years,…