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Drug Facts

What Are the Long-Term Health Effects of Marijuana Use?

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The Brain

When people smoke marijuana for years, they can suffer some pretty negative consequences. For example, because marijuana affects brain function, your ability to do complex tasks could be compromised, as well as your pursuit of academic, athletic, or other life goals that require you to be 100-percent focused and alert. In fact, people who use marijuana over the long term report less life satisfaction, poorer education, and job achievement, and more interpersonal problems compared to people who do not use marijuana.

Marijuana also may affect your mental health. Studies show that early marijuana use may increase your risk of developing psychosis if you have a genetic vulnerability to the disease. Psychosis is a severe mental disorder in which there is a loss of contact with reality, including false ideas about what is happening (delusions) and seeing or hearing things that aren’t there (hallucinations). Marijuana also has been associated with depression and anxiety, but more research is necessary to confirm and better understand that relationship.

Addiction

Many people don’t think of marijuana as addictive—they are wrong. About 9 percent of people who use marijuana become dependent on it. The number increases to about one in six among those who start using it at a young age, and to 25 to 50 percent among daily users. Marijuana increases dopamine, which creates the good feelings or “high” associated with its use. A user may feel the urge to smoke marijuana again, and again, and again to re-create that experience. Repeated use could lead to addiction—a disease where people continue to do something, even when they are aware of the severe negative consequences at the personal, social, academic, and professional levels.

People who use marijuana may also experience a withdrawal syndrome when they stop using the drug. It is similar to what happens to tobacco smokers when they quit—people report being irritable, having sleep problems, and weight loss—effects which can last for several days to a few weeks after drug use is stopped. Relapse is common during this period, as users also crave the drug to relieve these symptoms.

Lungs and Airways

People who abuse marijuana are at risk of injuring their lungs through exposure to respiratory irritants found in marijuana smoke. The smoke from marijuana contains some of the same chemicals found in tobacco smoke; plus, marijuana users tend to inhale more deeply and hold their breath longer, so more smoke enters the lungs. Not surprisingly, people who smoke marijuana have some of the same breathing problems as those who smoke tobacco—they are more susceptible to chest colds, coughs, and bronchitis than people who do not smoke.