What is marijuana use?

The two most active chemicals in marijuana are THC and CBD. THC affects how you think, act, and feel. It can make you feel very happy or "high." CBD can help you feel relaxed without the "high." Marijuana products usually contain both THC and CBD.

THC usually can be found in urine for a few days after marijuana is used. If you regularly use a lot of marijuana, THC may be found for weeks after use has stopped.

There are many types, or strains, of marijuana. Each strain has specific THC-to-CBD ratios. Because of this, some strains have different kinds of effects than others. For example, if a strain of marijuana has a higher ratio of THC to CBD, it's more likely to affect your judgment, coordination, and decision making.

In the United States, it's against federal law to possess, sell, give away, or grow marijuana for any purpose. But many states allow people with certain health problems to buy or grow it for their own use. And some states allow people over age 21 to use it for recreational reasons. Medical marijuana may be prescribed for teens with certain medical conditions. But recreational marijuana by teens is illegal everywhere in the United States.

Many schools and employers have strict rules about drug use. A positive drug test might cause you to be expelled from school or keep you from getting into a school you want to attend. You might not be able to take part in school sports or clubs. Or it might cause you to lose a job or keep you from getting hired.

If you use marijuana, take steps to lower your risk.

• To have the lowest risk, don't use marijuana. But if you do use it, limit your use.
• Know what you're using. Choose products that have low levels of THC. The type (or strain), strength, and effects of marijuana can vary greatly. And understand that how soon you may feel the effects of the product you use and how long those effects may last can vary. It depends on how you take it.
• Don't drive or operate machinery after you use marijuana. Using marijuana may affect your judgment, coordination, and decision making.
• Don't smoke marijuana. The smoke can damage your lungs.
• Don't use marijuana with alcohol, tobacco, or illegal drugs.
• Don't use synthetic marijuana, such as K2 and Spice. They can have very bad side effects.
• Reduce the risk of medicine interactions. Marijuana can be dangerous if you take it with blood thinners or with medicines that make you sleepy, control your mood, or lower your blood pressure.
• Keep others safe. Store marijuana in a safe and secure place. This is especially important with edible marijuana, which can be easily mistaken for treats or snacks. Make sure that children, friends, family, and pets can't get to it. And protect others from secondhand smoke.

Long-term use of marijuana may increase the risk of problems such as:

• Trouble with learning, memory, and concentration. This is most likely if regular heavy use starts in the teen years.
• Lung problems if you smoke marijuana. This can lead to coughing or wheezing and lung infections like bronchitis.
• Mental health problems like anxiety, depression, and psychosis. This is more likely if you have a personal or family history of these disorders or use marijuana products that have high levels of THC.
• Cannabis use disorder. Some people who use marijuana may find it hard to control their use. They may keep using marijuana even though it's having harmful effects on their lives. The disorder can range from mild to severe. People who use marijuana often and then quit may have withdrawal symptoms. These symptoms include anxiety, trouble sleeping, and intense cravings for the drug. The risk of this disorder is higher in people who:
  • Start using marijuana when they're young.
  • Use it every day.
  • Have other substance use disorders and mental health problems.
• Increased risk for severe nausea and vomiting (cannabinoid hyperemesis syndrome, or CHS). People who have CHS may feel very thirsty and have belly pain and diarrhea. They may vomit more than 20 times a day. Bouts of vomiting may last more than 24 hours.