Marijuana: Additional health effects for adults

Heavy use is defined as daily or near daily marijuana use. Research has shown that long-term and/or heavy use of marijuana can cause:

  • Brain and mental health effects:
    • Heavy use of marijuana can damage your memory. This damage can last a week or more after the last time you used.

    • Marijuana, especially in high doses, can cause people who are high to not know what is real, have hallucinations and paranoia. This is called temporary psychosis.

    • Heavy use of marijuana may lead to development of psychotic disorders, such as schizophrenia.

  • Respiratory effects:

    • Marijuana smoke irritates the lungs.

    • People who smoke marijuana daily or near-daily may have a daily cough, bronchitis, mucus and wheezing.

    • Both firsthand and secondhand smoke contain the same cancer-causing chemicals as tobacco smoke.

  • Cancer:

    • There is conflicting research about smoking marijuana and lung cancer.

    • The cancer-causing chemicals in tobacco smoke are also in marijuana smoke.

    • People who smoke marijuana daily or near-daily may have tissue damage in the airways of their lungs. More research is needed to determine if this tissue damage increases the likelihood of developing lung cancer.

    • Adults who use marijuana may be at a higher risk of certain types of testicular cancer. 

  • Other Health Effects:
    • Some people who use marijuana heavily can start vomiting without being able to stop; this is called Cannabinoid Hyperemesis Syndrome. This can be reversed by stopping marijuana use.

    • Using marijuana may increase the risk of stroke in adults who are younger than 55.

All information on the health effects of marijuana is taken from the Retail Marijuana Public Health Advisory Committee’s systematic review of available, high-quality research.