Long-Term Health Effects of Smoking Marijuana

Marijuana rolled into joints
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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 and legalization 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 less secrecy and more availability around marijuana use doesn’t necessarily mean it’s always safe for recreational use.

Scientists are just beginning to understand the complex ways 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) showed 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.

Breathing Problems

Although marijuana and tobacco are two entirely different substances, smoking either can have similar effects on the lungs. Like cigarette smokers, pot smokers are also at greater risk of chest colds, bronchitis, 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 and 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 marijuana is smoked (with the person often holding it in after inhaling it), it’s easy to imagine why, puff for puff, smoking marijuana may increase the risk of cancer more than smoking tobacco does.

However, as of yet, population studies have failed to find a clear increased risk of lung cancer in marijuana use. Complicating this assessment is that many people who smoke pot also smoke cigarettes and may use other substances.

Testicular Cancer

Smoking marijuana may be particularly dangerous for younger men. Some studies suggests a link between an increased risk of a particular type of testicular cancer and marijuana use.

A 2015 study in the peer-reviewed journal BMC Cancer concluded that using cannabis once a week or for more than 10 years was associated with an increased risk of testicular germ cell tumors, or TGCTs).

Heart Problems

Within minutes of smoking pot, your heartbeat increases and you can experience a change in your blood pressure, which can be dangerous for people with heart disease. Researchers have found that people who use marijuana have a greater risk of heart attack after smoking as compared to people who don't.

Studies have also found a link between marijuana use and arrhythmias, as well as a potentially increased risk of a stroke.

Cannabinoids can also potentially 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, people who regularly used marijuana had an increased risk of reduced bone density, which can increase the risk of 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 potentially 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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