The Health Risks of Marijuana

  • Marijuana can negatively affect memory, attention span, and psychomotor performance
  • The most significant public health impact of marijuana is the risk of motor vehicle accidents – rates of marijuana-impaired driving are higher than rates of alcohol-impaired driving
  • Regular long-term smoking is linked to bronchitis and cancer
  • Marijuana is thought to increase the likelihood of mental illness in people with a pre-existing vulnerability and to exacerbate symptoms in people who are already mentally ill
  • At the level of use reported by most adult users, the health risks are modest – significantly lower than tobacco or alcohol – though the more frequent the use, the greater the chance of harm
  • There is strong evidence that regular marijuana use in adolescence can seriously harm the developing brain, and these effects may not be reversible
  • If you smoke marijuana, the effects last for several hours, but the active ingredient (THC) can stay in your body for weeks – this could affect your memory, speech and learning
  • Research has shown that marijuana can relieve nausea and vomiting, and can help restore appetite 

Source: CAMH Cannabis Policy Framework, October 2014