Long-term health effects for adults

Research has shown that long-term use of marijuana can cause:

  • 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.

  • Lung 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. 

  • 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 temporary psychosis (not knowing what is real, hallucinations and paranoia) while you are high.

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. For more information about its findings, review Monitoring Health Concerns Related to Marijuana in Colorado.