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Substance Abuse and Addiction Health Center

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Marijuana - Topic Overview

What is marijuana?

Marijuana is a drug that is made up of the leaves, flowers, and buds of the hemp plant Cannabis sativa. It is often smoked in pipes or hand-rolled cigarettes. But it can also be vaporized, applied to the skin, cooked in food, or brewed into tea.

In the United States, several states have made some forms of marijuana legal, mainly as a medical treatment. It may be used for symptoms like pain, nausea, and lack of appetite. But possession of marijuana is still a crime under federal law.

What are the short-term effects of marijuana?

People often use marijuana for the way it makes them feel. 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.

But it may also cause unwanted side effects, such as:

The immediate effects of marijuana depend on the potency of its main active chemical, THC. THC affects areas of the brain that are involved in important functions such as memory, concentration, and coordination.

How quickly the effects start depends on several things, including how it was taken. When marijuana is smoked, the effects can usually be felt within seconds after inhaling. The effects last about 2 to 3 hours.

Marijuana is absorbed by fatty tissues in various organs of the body. THC usually can be detected in urine several days after marijuana has been smoked. If marijuana use is heavy, THC may be found in urine for weeks after use has stopped.

What are the long-term effects of marijuana use?

Long-term regular use of marijuana may cause problems such as:

  • Trouble with learning and memory. This is most likely if regular heavy use begins in the teen years.
  • Reduced lung function. This can lead to coughing or wheezing.
  • An increased risk of lung cancer. But the risk seems to be much less than the risk from smoking tobacco.
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