Mary P. Andersen, M.S.
Marijuana is also called pot, grass, weed or dope. It causes many
health problems. Because it was not often used in our culture until
recent decades, many of these effects are only beginning to be
understood. In the past, marijuana was used mostly by men. The
effects, especially for the long-term, of recent increased
marijuana use among children and women are still largely unknown.
Also, marijuana today contains much higher concentrations of the
active ingredient, THC (delta-9-Tetrahydrocannabinol), which causes
the "high." THC, also found in hashish, is responsible for many of
the bad effects of marijuana.
Division of Pulmonary, Critical Care and Environmental Medicine,
University of Missouri, Columbia, Mo. 65212
Marijuana temporarily affects vision, hearing, judgement, memory,
and sense of time. The impairment lasts longer than the feeling of
being "high," so users may try to drive or do other things when
they should not. Marijuana users are more likely to be involved in
fatal crashes than nonusers. Temporary effects last several days.
Marijuana affects behavior. Heavy users are less likely to
socialize, set or achieve goals. Pre-employment drug screens
positive for marijuana use are linked to higher job turnover,
accidents, injuries, discipline problems and absenteeism.
Marijuana users have measurable changes in their brains. These
include temporary changes in the electrical brain waves, called
EEG's, and permanent brain abnormalities whose meaning is not yet
In high doses or especially among people who have mental disorders,
using marijuana even once may cause extreme anxiety, paranoia, or
hallucinations. Mental illnesses, such as schizophrenia, may appear
or worsen with marijuana use. Epileptic seizures are also linked to
Marijuana smoke causes cancer. It is more carcinogenic than tobacco
REPRODUCTION AND DEVELOPMENT
Marijuana decreases sex hormones, weight of the sexual organs, and
sexual appetite. Sperm of marijuana users are fewer, and are
abnormal in structure and function. Women who use marijuana also
have lower fertility and are more likely to have a miscarriage.
Marijuana compounds cross the placenta and affect fetal
development. They also pass into a mother's milk. Babies born to
women who use marijuana may have low birth weight, physical and
mental defects resembling fetal alcohol syndrome, and inadequate
sex differentiation or development.
Marijuana smoke causes lung damage similar to cigarette smoke.
However, marijuana is more harmful to lung function than tobacco
cigarettes. Marijuana smoke is also far more irritating to the
sinuses, throat and lungs than tobacco smoke. Marijuana smoke
damages alveolar macrophages, an important part of the immune
system in the lungs.
HEART AND CIRCULATORY SYSTEM
Smoking marijuana is a serious risk for people with hypertension,
heart and cerebrovascular diseases. These people should not use
Mild physical dependence often results from marijuana use.
It is illegal for most people to use, possess, grow, buy or sell
marijuana. Marijuana can legally be prescribed by a physician to
treat cancer patients for the nausea and poor appetite caused by
chemotherapy. Other drugs are more effective, but for those unable
to tolerate such drugs, marijuana or THC may be helpful. Marijuana
also can help patients with glaucoma. However, other drugs usually
have less harmful side effects than marijuana.
There are good reasons not to use marijuana even once:
It is dangerous for driving, can cause memory problems, may have
psychotic effects, and is dangerous for people with heart or
circulatory problems. Women who are pregnant or nursing should
never use marijuana. Since marijuana is illegal, there is no way to
guarantee that what appears to be marijuana is in fact marijuana,
or in what concentration the active ingredient THC may be found.
There are good reasons to avoid chronic use of marijuana:
It retards social development and motivation, learning and
intellect; reduces fertility and sex drive; causes cancer, lung
disease, birth defects, and miscarriages; retards growth; decreases
body weight, and causes physical dependence.
For more information, call the Natl. Inst. for Drug Abuse (NIDA)
Natl. Clearinghouse for Alcohol and Drug Information 800-729-6686
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