Marijuana is viewed by some people as a harmless drug. Although it can bring on pleasurable feelings and may have medicinal benefits, it can also have bad side effects such as interfering with thinking and perception. Marijuana use may also cause serious health problems. The damage it causes can become intense over time, leading to social and personal difficulties for the user.
Memory problems, learning difficulties, trouble with problem solving and loss of muscle activity are among the negative effects of short-term use of marijuana, according to the Partnership for a Drug-Free America (PDFA). Other serious results include increased heart rate and anxiety. Marijuana smokers face the same problems as tobacco smokers, including coughing and breathing trouble.
The same risks smokers of tobacco face may also threaten marijuana users over a long period of time. There are cancer-causing chemicals in marijuana that can be in higher concentrations than tobacco, the PDFA says, adding that smoking five joints a week is the equivalent of smoking a pack of cigarettes a day. Smoking marijuana, like smoking tobacco, may cause lung diseases, according to the National Women's Health Information Center. Marijuana use can reduce the immune system's ability to fight disease.
THC, the main active ingredient in marijuana, is carried from the bloodstream to the brain and other organs of the body, according to the National Institute on Drug Abuse (NIDA). It causes chemicals in the brain to bring about the pleasurable effects of marijuana. But areas of the brain that control thoughts, concentration, sensory perception and coordination are also affected. When these areas are disturbed it can impair coordination and mental abilities. The problems can continue for days or weeks after the drug effects wear off, the NIDA says. Long-term use of marijuana may have the same effect on the brain as other drugs, causing a loss of motivation and behavioral problems.
Long-term marijuana users may develop a dependency on the drug that interferes with family life, career, school and social functioning, the NIDA says. The addiction to marijuana is evident from the withdrawal symptoms a marijuana user experiences when quitting. Symptoms include irritability, anxiety, insomnia and craving for the drug. The symptoms can continue for days, but subside in one or two weeks following cessation from marijuana.
Anxiety, panic attacks and paranoia can result from short-term marijuana use, according to the NIDA. Chronic marijuana use may increase risks for mental illness. Long-term use may lead to anxiety disorder, depression and schizophrenia, the NIDA says. It is not entirely clear if marijuana causes these disorders, exacerbates them or is used to self-medicate existing problems in different cases.