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What is cannabis? Cannabis also known as grass, pot, weed, cannabis, dope, hash, chronic (and many more names!), is the most widely used illicit drug in Ontario and Canada. Marijuana is usually green/brown/grey coloured and comes from the dried flower buds and leaves of the cannabis plant. The main active ingredient in marijuana is THC (delta-9-tetrahydrocannabinol), which is the chemical responsible for the “high” experienced by users.



Marijuana has been linked to many health and social problems. This is especially true with youth and frequent users. Research has shown that marijuana use can negatively affect a person’s life including:

  • physical and mental health problems
  • decreased cognitive functioning (memory, attention, and problem solving)
  • impair the ability to drive a vehicle
  • reproductive health issues

The Risks

Learn about the Risks of Marijuana. If you're concerned about your marijuana use or marijuana use of a friend or family member, check out the following resources and supports.


Additional Information

Learn about the health and social effects of marijuana, the myths and facts about marijuana, how to talk to your kids about drug use and resources to get help with marijuana use.

Date of creation: February 1, 2013
Last modified on: January 9, 2018


1Partnership for a Drug Free Canada. (2013). Marijuana. Retrieved from
2Centre for Addiction and Mental Health. (2010). Marijuana (Cannabis). Retrieved from
3Canadian Centre on Substance Abuse. (2010). Clearing the Smoke on Cannabis Series: Highlights. Retrieved from