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What is marijuana?

Marijuana is a plant also known as hemp. People sometimes use marijuana to get high, or intoxicated. The flowers, stems, seeds, and leaves of the marijuana plant can be dried and shredded and then smoked. People can smoke marijuana in the form of cigarettes (also called, joints or blunts) or by inhaling the smoke from bongs (water pipes). You may hear of other kinds of marijuana, such as Hashish, which is the resin of the hemp plant. There are over 200 slang names for marijuana, including pot, weed, gangster, or chronic. It is the most commonly used drug after alcohol.

How does it work?

A chemical in the plant called delta-9-tetrahydrocannabinol, or THC, changes a person's body chemistry. The chemical is absorbed through the lungs and goes into the blood. THC causes the brain to release a chemical that makes a person feel "high." THC stays in the body's organs for several days. Marijuana is much more potent then it used to be. A joint has 10 times more THC in it now then it did back in the 60s and 70s. This can cause very serious health problems.

Who uses marijuana?

Some people say that "all high school kids use marijuana." This is definitely not the case. The majority of kids in school do not use marijuana. In 2001, only 6% percent of high school seniors reported that they used marijuana every day. Although most kids don't use marijuana, many have tried it. Twenty percent of 8th graders, 40% of 10th graders, and 49% of 12th graders say they have tried marijuana.

Why do teens use marijuana?

There are a variety of reasons teens choose to get high. Some use because of peer pressure -- trying to find a way to fit in with a group of peers. Some do it because they think that all teenagers get high. Some do it for fun. Often teenagers choose to get high because of stress in their life. It lets them temporarily escape from a stressful situation, or forget about the days problems. Many choose to get high because it lets them "chill" or relax.

Frequently doctors find that teens who get high are dealing with depression, a difficult family situation, or anxiety. Teens end up self-medicating with marijuana, rather than seeking help from a professional. Unfortunately, this can cause major problems that the teenager does not anticipate.

What effects does marijuana have on the body?

  • Brain: Short term effects include a distorted perception of reality, difficulty with memory and learning, trouble problem solving and thinking clearly, and loss of motor coordination (reflexes and quickness). There are significant long term effects of marijuana use as well. Marijuana use can cause memory and learning problems for weeks after using it.
  • Emotional: There are higher rates of depression and anxiety among marijuana users. Daily problems often get worse, as marijuana can cause a teen to not deal with issues. Relationships get worse and job and school performance suffers. Your teen may develop a lack of interest in life, school, family, and friends.
  • Lungs: There are multiple cancer-causing agents and tars in marijuana which are similar to those in tobacco cigarettes. Marijuana smoke contains 50% to 70% more cancer-causing hydrocarbons than tobacco smoke. Marijuana users inhale deeply and keep the smoke in much longer than tobacco users. This increases the amount of tars and chemicals that are deposited in the lungs. And because marijuana smoke is not filtered, one joint is equal to 10 to 40 tobacco cigarettes. Marijuana smokers have more chronic coughs and lung infections than nonsmokers.
  • Heart: Marijuana can increase blood pressure and heart rate. Because of the carbon monoxide inhaled, blood is less able to carry oxygen.
  • Immune System: THC can change the way the body fights infection and cancer.
  • Pregnancy: Smoking marijuana while pregnant can cause lasting effects on a child. The baby may not develop normally. The child can have more behavioral problems and poorer performance on language comprehension, attention, and memory. Children are at a significant disadvantage if exposed to smoke during pregnancy.

What about medical marijuana?

THC is used occasionally to help people with certain eye problems or severe pain from cancer. In these cases, a doctor can legally prescribe a pill form of THC. This is only legal in only a few states.

Does using marijuana affect driving?

In a word, yes. Because THC affects parts of the brain that control coordination and reaction time. Even a small amount of THC impairs driving ability. If combined with alcohol driving performance decreases even more dramatically.

Can my teen become addicted to marijuana?

Yes. Contrary to popular belief, marijuana is addictive. Often, a teen's use of marijuana turns from an occasional use into daily use. Teens start to need marijuana to deal with the day. People dependent on marijuana, like those dependent on other addictive drugs, have trouble quitting. They also have withdrawal symptoms, such as irritability, anger, depressed mood, headaches, restlessness, lack of appetite, and drug craving. This can make it difficult to stop using the drug.

Does marijuana use lead to other drug use?

Often, marijuana is referred to as a gateway drug. It is usually the first illegal drug a teenager tries. Not all people who use marijuana go on to use other drugs, but it is a risk. The younger people are (12,13, or 14 years old) when they use marijuana for the first time, the greater the chance that they will go on to try "harder" drugs such as ecstasy, methamphetamine, mushrooms, LSD, cocaine, or heroin. An additional concern is that people may mix in these other drugs with marijuana, without your teen even knowing it.

How can I tell if my teen is smoking marijuana or if it is affecting their life?

This is a complex question and evaluation. You may be able to notice changes in your teen's life.

  • Have your teen's grades gone down?
  • Has he or she dropped out of school?
  • Have relationships with friends or family gotten worse? Is your teen fighting or arguing more?
  • Does your teen seem tired, anxious, or depressed?
  • Has your teen changed friends or stopped seeing his or her old friends?
  • Has your teen gotten in trouble with the law?
  • Does your teen seem to have unexplained headaches, stomachaches, or nosebleeds?
  • Has your teen started sleeping more, or less?
  • Is your teen asking for more money or trying to steal your money?

If you have answered YES to any of these questions, then your teen may need help.

How can I help my teen?

There are many ways to seek help. Talk to your teen about the problem. Call the school counselor and ask for help and guidance about substance use programs. Frequently schools have drug counseling classes. Your health care provider can help assess the severity of your teen's drug use problem and help you decide whether your teen would benefit from an outpatient drug treatment program or a more intensive inpatient setting. A health care provider can help sort out whether your teen is depressed, has ADHD, or another psychological problem that needs treatment.

Written by Eric Sigel, MD.
Published by McKesson Provider Technologies.
Last modified: 2006-10-10
Last reviewed: 2006-05-01
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright 2006 McKesson Corporation and/or one of its subsidiaries. All Rights Reserved.
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