Marijuana

Canada’s Lower-Risk Cannabis Use Guidelines

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There is strong scientific evidence that cannabis use is associated with a variety of health risks. The risks depend on your constitution, which kinds of cannabis products you use and how or how often you use them. Some of the main health risks are:

  • problems with thinking, memory or physical co-ordination
  • impaired perceptions or hallucinations
  • fatal and non-fatal injuries, including those from motor-vehicle accidents, due to impairment
  • mental health problems and cannabis dependence
  • chronic respiratory or lung problems
  • reproductive problems

Recommendations

  • Cannabis use has health risks best avoided by abstaining
  • Delay taking up cannabis use until later in life
  • Identify and choose lower-risk cannabis products
  • Don’t use synthetic cannabinoids
  • Avoid smoking burnt cannabis—choose safer ways of using
  • If you smoke cannabis, avoid harmful smoking practices
  • Limit and reduce how often you use cannabis
  • Don’t use and drive, or operate other machinery
  • Avoid cannabis use altogether if you are at risk for mental health problems or are pregnant
  • Avoid combining these risks

What are marijuana's long-term effects on the brain?

(Source: National Institute on Drug Abuse)

Substantial evidence from animal research and a growing number of studies in humans indicate that marijuana exposure during development can cause long-term or possibly permanent adverse changes in the brain.

Imaging studies of marijuana’s impact on brain structure in humans have shown conflicting results. Some studies suggest regular marijuana use in adolescence is associated with altered connectivity and reduced volume of specific brain regions involved in a broad range of executive functions such as memory, learning, and impulse control compared to people who do not use. Other studies have not found significant structural differences between the brains of people who do and do not use the drug.

Several studies, including two large longitudinal studies, suggest that marijuana use can cause functional impairment in cognitive abilities but that the degree and/or duration of the impairment depends on the age when a person began using and how much and how long he or she used.

The ability to draw definitive conclusions about marijuana’s long-term impact on the human brain from past studies is often limited by the fact that study participants use multiple substances, and there is often limited data about the participants’ health or mental functioning prior to the study.