What is Marijuana?
Marijuana is a green, brown, or gray mixture of dried, shredded leaves, stems, seeds, and flowers of the hemp plant. You may hear marijuana called by street names such as pot, herb, weed, grass, boom, Mary Jane, gangster, or chronic. There are more than 200 slang terms for marijuana.
Sinsemilla (sin-seh-me-yah; it's a Spanish word), hashish ("hash" for short), and hash oil are stronger forms of marijuana.

All forms of marijuana are mind-altering. In other words, they change how the brain works. They all contain THC (delta-9-tetrahydrocannabinol), the main active chemical in marijuana. They also contain more than 400 other chemicals. Marijuana's effects on the user depend on the strength or potency of the THC it contains.(5) THC potency of marijuana has increased since the 1970s but has been about the same since the mid-1980s.

How is marijuana used?
Marijuana is usually smoked as a cigarette (called a joint or a nail) or in a pipe or a bong. Recently, it has appeared in cigars called blunts.

How long does marijuana stay in the user's body?
THC in marijuana is strongly absorbed by fatty tissues in various organs. Generally, traces (metabolites) of THC can be detected by standard urine testing methods several days after a smoking session. However, in heavy chronic users, traces can sometimes be detected for weeks after they have stopped using marijuana.

How many teens smoke marijuana?
Contrary to popular belief most teenagers have not used marijuana and never will. Among students surveyed in a yearly national survey, only about one in five 10th graders report they are current marijuana users (that is, used marijuana within the past month). Fewer than one in four high school seniors is a current marijuana user.

Why do young people use marijuana?
There are many reasons why some children and young teens start smoking marijuana. Most young people smoke marijuana because their friends or brothers and sisters use marijuana and pressure them to try it. Some young people use it because they see older people in the family using it.

Others may think it's cool to use marijuana because they hear songs about it and see it on TV and in movies. Some teens may feel they need marijuana and other drugs to help them escape from problems at home, at school, or with friends.

No matter how many shirts and caps you see printed with the marijuana leaf, or how many groups sing about it, remember this: You don't have to use marijuana just because you think everybody else is doing it.

What are the long-term effects of marijuana use?
Findings so far show that regular use of marijuana or THC may play a role in some kinds of cancer and in problems with the respiratory, and immune systems.

Does marijuana lead to the use of other drugs?
It could. Long-term studies of high school students and their patterns of drug use show that very few young people use other illegal drugs without first trying marijuana. For example, the risk of using cocaine is 104 times greater for those who have tried marijuana than for those who have never tried it. Using marijuana puts children and teens in contact with people who are users and sellers of other drugs. So there is more of a risk that a marijuana user will be exposed to and urged to try more drugs.

To better determine this risk, scientists are examining the possibility that long-term marijuana use may create changes in the brain that make a person more at risk of becoming addicted to other drugs, such as alcohol or cocaine. While not all young people who use marijuana go on to use other drugs, further research is needed to predict who will be at greatest risk.

How can you tell if someone has been using marijuana?
If someone is high on marijuana, he or she might: seem dizzy and have trouble walking; seem silly and giggly for no reason; have very red, bloodshot eyes; and have a hard time remembering things that just happened. When the early effects fade, over a few hours, the user can become very sleepy.

If a woman is pregnant and smokes marijuana, will it hurt the baby?
Doctors advise pregnant women not to use any drugs because they could harm the growing fetus. One animal study has linked marijuana use to loss of the fetus very early in pregnancy.

Some scientific studies have found that babies born to marijuana users were shorter, weighed less, and had smaller head sizes than those born to mothers who did not use the drug. Smaller babies are more likely to develop health problems. There are also research data showing nervous system problems in children of mothers who smoked marijuana.

Researchers are not certain whether a newborn baby's health problems, if they are caused by marijuana, will continue as the child grows. Preliminary research shows that children born to mothers who used marijuana regularly during pregnancy may have trouble concentrating.

What does marijuana do to the brain?
Some studies show that when people have smoked large amounts of marijuana for years, the drug takes its toll on mental functions. Heavy or daily use of marijuana affects the parts of the brain that control memory, attention, and learning. A working short-term memory is needed to learn and perform tasks that call for more than one or two steps.

Smoking marijuana causes some changes in the brain that are like those caused by cocaine, heroin, and alcohol. Some researchers believe that these changes may put a person more at risk of becoming addicted to other drugs, such as cocaine or heroin. Scientists are still learning about the many ways that marijuana could affect the brain.

Can people become addicted to marijuana?
Yes. While not everyone who uses marijuana becomes addicted, when a user begins to seek out and take the drug compulsively, that person is said to be dependent or addicted to the drug. In 1995, 165,000 people entering drug treatment programs reported marijuana as their primary drug of abuse, showing they need help to stop using the drug.

According to one study, marijuana use by teenagers who have prior serious antisocial problems can quicky lead to dependence on the drug.

Some frequent, heavy users of marijuana develop a tolerance for it. "Tolerance" means that the user needs larger doses of the drug to get the same desired results that he or she used to get from smaller amounts.

What if a person wants to quit using the drug?
Up until a few years ago, it was hard to find treatment programs specifically for marijuana users.

Now researchers are testing different ways to help marijuana users abstain from drug use. There are currently no medications for treating marijuana addiction. Treatment programs focus on counseling and group support systems. There are also a number of programs designed especially to help teenagers who are abusers. Family doctors are also a good source for information and help in dealing with adolescent marijuana problems.