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What are the side effects of marijuana?

Medically reviewed by Last updated on Nov 17, 2020.

Official Answer


Common side effects of using weed are; changes in blood pressure, increases in heart rate, dizziness or drowsiness, facial flushing, gastrointestinal disturbances, increased risk of developing a mood disorder, and some impairment in respiratory function.

Weed (pot/marijuana/Cannabis sativa) is now legal in the majority of states as medical marijuana. Some states have legalized recreational pot use as well.

Weed may be used to help relieve chronic pain or nausea caused by chemotherapy. Some people believe it may also help reduce symptoms of multiple sclerosis, seizures, or some other conditions. But there is still a lot to learn about marijuana.

Researchers are still unsure about what long-term effects marijuana has on the mind and body, especially when given to children or adolescents.

The most common side effects of the weed are:

  • Changes in blood pressure (both low and high reported) and increases in heart rate
  • Dizziness or drowsiness
  • Facial flushing
  • A false sense of well-being or a feeling of being “high” or elation/laughing
  • Gastrointestinal disturbances (eg, nausea, vomiting, abdominal pain)
  • Some impairment in respiratory function. May increase coughing or mucus production. Chronic use may increase the risk of asthma or COPD
  • Short-term impairment in learning, memory, and attention. Possible long-term impairment in mental skills with chronic use
  • Possibly associated with some cancers, such as testicular cancer. Association with other cancers less clear
  • May increase the risk of developing a mood disorder (such as anxiety, bipolar disorder, depression) or exacerbate pre-existing mood disorders
  • Tiredness/fatigue.

Babies born to mothers who have smoked weed while pregnant are more likely to be born prematurely, be underweight, or need intensive care.

Very little THC (the active ingredient in marijuana) is released in the air when marijuana smokers breathe out, so it is unlikely that second-hand marijuana smoke will cause you to fail a drug test.

See here for more information about the weed (marijuana).

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