What is marijuana?

Marijuana (cannabis) is a drug that's made up of the leaves, flowers, and buds of the cannabis plant. People may use marijuana for medical or recreational reasons. The two most active chemicals in marijuana are THC and CBD. THC can make you feel "high." CBD can help you feel relaxed without the "high."

What are the short-term effects of marijuana use?

People often use marijuana for the way it makes them feel. Or they may use it for medical reasons. Using it may make them:

  • Feel relaxed or very happy ("high").
  • Have less chronic pain or nerve (neuropathic) pain.
  • Feel hungry so they eat more.

Marijuana can also cause unwanted side effects, such as:

  • Impaired short-term memory and ability to concentrate.
  • Poor judgment and coordination.
  • Feeling anxious.
  • Paranoid thoughts.
  • Faster heart rate.
  • Red eyes and dry mouth.
  • Feeling dizzy.
  • Nausea and vomiting.
  • Changes in blood pressure.

What are the risks?

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.

Synthetic marijuana

Synthetic marijuana is made of dried plant material that is treated with chemicals that produce effects like marijuana's effects. It is sold in the form of incense under many names, such as K2 or Spice. The labels often claim that these products are "safe" or "natural." But in fact, the active chemicals are created in a lab. And they have not been tested for safety.

But young people often try these products because they are easy to buy and they may not be detected by drug tests.

People think that using these drugs will make them feel the same as when they use marijuana. But these drugs can be stronger than marijuana. And the effects are hard to predict. That's because the type and strength of the chemicals used are often unknown. Some people have reported severe symptoms, such as:

  • Fast heart rate and high blood pressure.
  • Vomiting.
  • Feeling agitated or confused.
  • Feeling like others want to harm them (paranoia), or seeing or hearing things that aren't there (hallucinations).


Current as of: November 15, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.