Marijuana affects your brain. THC (the active ingredient in marijuana) affects the nerve cells in the part of the brain where memories are formed.

Marijuana affects your self-control. Marijuana can seriously affect your sense of time and your coordination, impacting things like driving. In 2005, nearly 242,200 people were admitted to emergency rooms suffering from marijuana-related problems.

Marijuana affects your lungs. Marijuana smoke deposits four times more tar in the lungs and contains 50 percent to 70 percent more cancer-causing substances than tobacco smoke does.

Marijuana affects other aspects of your health. Marijuana can limit your body’s ability to fight off infection. Heavy marijuana use also has been linked with depression, anxiety, and personality disturbances.

Marijuana is not always what it seems. Marijuana can be laced with substances such as PCP, formaldehyde, or codeine cough syrup without your knowledge. “Blunts”—hollowed-out cigars filled with marijuana—sometimes have crack cocaine added.
Marijuana can be addictive. Not everyone who uses marijuana becomes addicted, but some users do develop signs of dependence. In 2006, nearly 290,000 people entered drug treatment programs to kick their marijuana habit.

Before You Risk It…
Know the law. It is illegal to buy or sell marijuana. In most States, holding even small amounts of marijuana can lead to fines or arrest.
Get the facts. Smoking marijuana can cause health
problems, such as chronic coughing, chest colds, lung infections, breathing problems, and cancer.

Stay informed. It has not yet been proven that using marijuana leads to using other drugs, but most teens who try drugs start with marijuana, alcohol, or tobacco.

One study found that people who had used marijuana before the age of 17 were more likely to use other drugs and develop addiction problems later on.

Know the risks. Marijuana affects your coordination and reaction time, raising your risk of injury or death from car crashes and other accidents.

Keep your edge. Marijuana affects your judgment, drains your motivation, and can make you feel anxious.

Look around you. Most teens aren’t smoking marijuana. According to a 2006 study, about four out of five 12- to 17-year-old youths had never even tried marijuana.

Know the Signs…
How can you tell if a friend is using marijuana? Sometimes it’s tough to tell. But there are signs you can look for. If your friend has one or more of the following warning signs, he or she may be using marijuana:

Seeming dizzy and having trouble walking

Having red, bloodshot eyes and smelly hair and clothes

Having a hard time remembering things that just happened

Acting silly for no apparent reason

What can you do to help someone who is using marijuana or other drugs? Be a real friend. Encourage your friend to seek professional help. For information and referrals, call SAMHSA’s Health Information Network at 1-877-SAMHSA-7 (1-877-726-4727).

For more information or for references to facts found in this Tips for Teens, go to www.samhsa.gov/SHIN