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Long-Term Effects

Long-term and regular use of cannabis may affect people in a variety of ways including:

  • effects on the developing brain of young people, up to the age of 25 years,
  • effects on unborn/newborn children of pregnant or breastfeeding mothers,
  • impact on the lungs for those who smoke cannabis,
  • impact on mental health,
  • risk for addiction.

It is estimated that 1 in 11 (9%) cannabis users will develop an addiction. This statistic rises to about 1 in 6 (17%) for people who started using cannabis as a teenager. If a person smokes cannabis daily, the risk of addiction is 25% to 50%. (Health Canada 2017)

Individuals who develop an addiction to cannabis typically:

  • Want to use often, even when they didn't plan to
  • Spend a lot of time thinking about and using cannabis
  • Need a greater amount of cannabis to get the same effects
  • Continue to use cannabis even though it is causing physical or social problems

Research has shown that cannabis use impacts the development of psychosis in some individuals. Psychosis is a break with reality characterized by hallucinations, false beliefs (delusions), impaired thinking and lack of motivation. 


Regular use of cannabis can affect your lungs and lead to conditions such as cough, wheeze, worsening of asthma, sore throat, bronchitis, and lung infections. Cannabis smoke contains many of the same chemicals as tobacco smoke, several of which are known to cause cancer.

For additional tips on avoiding the smoking of cannabis click here.

See the Health Unit's September 2019 Health Fax for the latest information related to the health impacts on vaping.

Avoid cannabis use if you are pregnant, thinking of becoming pregnant or breastfeeding. There are potential harms to infant and child health. Talk to a health professional about cannabis and other drugs in pregnancy and breastfeeding. For more information see, or call MotherToBaby at 1-866-626-6847.
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