Long-Term Health Impacts

Health
Cannabis

New research studying the long-term health impacts of cannabis use continues to be published. In Colorado, the Colorado Department of Public Health and Environment must monitor the scientific data and medical literature on cannabis use patterns and health effects associated with use and present a report to their legislators every two years.

The Washington Legislature earmarked funding from cannabis taxes and fees for the University of Washington’s Addictions, Drugs, and Alcohol Institute to maintain a website dedicated to science-based information for the general public.


There is dedicated funding to support additional research into the health impacts of long-term use of cannabis, but because legalization is fairly recent, the longer-term studies will take time to complete and analyze.

Highlights from some recent studies include the following health-related information:

  • Mental health
    • Daily or near-daily cannabis use increases the chance of developing psychotic disorders, such as schizophrenia.
    • THC can cause acute psychotic symptoms such as hallucinations, paranoia, delusional beliefs, and feeling emotionally unresponsive during intoxication. These symptoms are worse with higher doses.
       
  • Cancer
    • Cannabis smoke, both firsthand and secondhand, contains many of the same cancer-causing chemicals as tobacco smoke.
    • Daily or near-daily cannabis smoking is strongly linked to pre-malignant lesions that my lead to cancer in the airways of the lungs.
    • Cannabis use increases risk of nonseminoma testicular cancer.
       
  • Cardiovascular
    • Cannabis use increases the risk of stroke in people younger than 55 years of age.
       
  • Hyperemesis syndrome (cannabis-related extreme vomiting)
    • Long-time, daily, or near-daily cannabis use is the cause of severe recurrent vomiting (cannabis hyperemesis syndrome) in some people who use cannabis frequently. Stopping use can prevent future episodes of vomiting.
       
  • Respiratory health for smoked cannabis
    • Daily or near-daily cannabis smoking is strongly associated with chronic bronchitis, including chronic cough, sputum production, and wheezing.
    • One-time cannabis use (smoked or edible) is strongly associated with immediate, short-term (1 to 6 hours) improved airflow in the lungs. 
       

Additional health impacts can be found in the full report from Colorado and on the Learn About Cannabis WA website.