Long-Term Health Affects of Smoking Marijuana

Man smoking a joint
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We’ve come a long way from the days when smoking marijuana was strictly a hush-hush activity. From increasing acceptance of recreational products made from pot to the use of medical marijuana to treat symptoms such as pain and nausea from chemotherapy, more and more people are being open about the role marijuana plays in their lives.

But although there's less secrecy around marijuana use, it doesn’t necessarily mean it’s safe for recreational use. Scientists don’t know how long-term marijuana use affects the body, but there are studies that suggest it can cause several health problems over time. For instance, preliminary animal and human studies suggest smoking marijuana can put a damper on the immune system. Here are other health problems that may be linked to using pot.

Cognitive Problems

The active ingredient in marijuana, delta-9 tetrahydrocannabinol or THC, acts on cannabinoid receptors found in brain regions that influence learning, memory, appetite, coordination, and pleasure.

Researchers are still learning the effects of long-term, chronic marijuana use on the brain, but they believe the strongest effects occur in young adults who are still developing neural connections. 

One study of teens found impaired neural connectivity in specific brain regions involved in a broad range of executive functions like memory, learning, and impulse control compared to non-users.

Teens who smoked pot regularly—daily for three years—had changes to the hippocampus, which is the part of the brain responsible for long-term memory. Researchers found that the longer (and more chronically) study participants used marijuana, the more abnormal the shape of their hippocampus, resulting in poor long-term memory for at least several years after last use.

Breathing Problems

Although marijuana and tobacco are two entirely different substances, smoking either has similar effects on the lungs. These can be more severe for pot smokers because they tend to inhale more deeply. What's more, in order to bring about a high, they tend to hold the smoke in their lungs for as long as possible. This increases the amount of smoke the lungs are exposed to, putting them at even greater risk of certain respiratory problems than tobacco smokers, or aggravating any preexisting conditions like asthma or cystic fibrosis.

For example, they may have increased production of phlegm leading to frequent coughing, and they may be especially prone to obstructed airways. Pot smokers also are at greater risk of chest colds and lung infections.

Vaping marijuana was previously believed to be a safer route of ingestion than smoking, but we now know that it can cause e-cigarette or vaping product use-associated lung injury (EVALI), a lung condition that causes breathing difficulties that can lead to hospitalization and even death.

Cancer

While coughing and colds are at the most annoying and inconvenient side effects of smoking marijuana, an increased risk of lung cancer is a life-threatening one. Marijuana smoke contains some of the same cancer-causing compounds as tobacco—sometimes in higher concentrations. Given the way pot smokers hold in smoke after inhaling it, it’s easy to see why, puff for puff, smoking marijuana may increase the risk of cancer more than smoking tobacco does.

The important word here is “may.” It's a challenge for researchers to figure out whether cannabis alone causes cancer because many people who smoke pot also smoke cigarettes and use other drugs. Tobacco smoke and marijuana smoke may work together to change the tissues lining the respiratory tract.

Testicular Cancer

Smoking marijuana may be particularly dangerous for men in the long term. A number of studies suggest a link between an increased risk of testicular cancer, the most common cancer among males under 45. A 2015 study in the peer-reviewed journal BMC Cancer concluded that using cannabis once a week or for more than ten years was associated with an increased risk of testicular cancer (particularly testicular germ cell tumors, or TGCTs).

Heart Problems

Within minutes of smoking pot, your heartbeat increases by 20% to 100% and you experience a slight drop in your blood pressure, which can be dangerous for people with heart disease. Researchers found that marijuana users have a four to five times greater risk of heart attack in the hour after smoking as compared to non-users.

Studies have also found a link between marijuana use and atrial fibrillation as well as the risk of a stroke. Marijuana is thought to alter the linking of blood vessels and alter blood flow.

Cannabinoids can also interfere with the effects of many drugs taken for heart disease, including antiarrhythmics, statins, calcium-channel blockers, beta blockers, and warfarin.

Bone Health

Research is still mixed on the impact of marijuana on your bone health. According to a 2017 study published in the American Journal of Medicine, chronic pot users have an increased risk of reduced bone density, which can increase the risk bone fractures.

Yet another study in the same year, published in Archives of Osteoporosis, found no link between marijuana use and decreased bone density.

Mental Health

Chronic smoking of high-potency marijuana has been found to increase the chances of psychosis (by nearly five times) compared to those who have never used the drug. Younger people in their teens and early twenties are particularly vulnerable to developing psychosis after using marijuana. Heavy use of marijuana in adolescence (particularly in teenage girls) has also been found to be a predictor of depression and anxiety later on in a person's life.

Despite what many people believe, marijuana is addictive and chronic, long-term use can result in cannabis use disorder. Roughly one in 12 marijuana users will eventually become addicted to the drug. Some people go for years living with marijuana addiction without realizing before they seek help.

If you or a loved one are struggling with substance use or addiction, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.

For more mental health resources, see our National Helpline Database.

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