Manitoba Addictions Knowledge Exchange



Cannabis – Information & Resources

According to a 2013 UNICEF Office of Research report, Canadian youth are the top users of cannabis (marijuana, weed) in the developed world.  Alcohol is the only drug used more frequently by Canadian youth.  According to Statistics Canada’s Canadian Tobacco, Alcohol and Drug Survey (CTADS), the number of youth (21%) and young adults (30%) who used cannabis in 2015 was more than two and a half times that of adults 25 and older (10%). Many of the past year users of cannabis reported using it on a daily or almost daily basis (33%).

Despite widespread belief amongst Canadians that cannabis use is not harmful, it is not a benign drug.  Cannabis use can negatively affect both physical and mental health, brain function (memory, attention & thinking) and driving performance.  For decades, cannabis plants have been selectively bred for increasing levels of its active ingredient tetrahydrocannabinol, or THC. Higher levels of THC are associated with increased likelihood of experiencing harms from cannabis use.  Frequent use (daily or almost daily) is also a strong predictor of problems related to cannabis use.

The Canadian Lower-Risk Cannabis Use Guidelines (see below) outline the main health risks associated with cannabis use.  The risks depend on a person’s physical health, the type of cannabis products used, and how often the products are used.  These risks include:

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

As we prepare for the legalization of cannabis in Canada in 2018, it is important to ensure that accurate information about cannabis is available to make informed choices about its use.  The following resources provide evidence-based information about various aspects of cannabis use.

Canada’s Lower-Risk Cannabis Use Guidelines (LRCUG)

The Lower-Risk Cannabis Use Guidelines are an evidence based intervention project by the Canadian Research Initiative in Substance Misuse (CRISM).  The recommendations are aimed mostly at non-medical cannabis use.  They have been endorsed by:

  • Centre for Addiction & Mental Health
  • Canadian Centre on Substance Misuse & Addiction
  • Canadian Medical Association
  • Canadian Public Health Association
  • Canadian Society of Addiction Medicine
  • Council of Chief Medical Officers of Health (in principle)

The science-based recommendations of the LRCUG aimed at reducing health risks related to cannabis use include:

  • 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 burned 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

For more details about the LRCUG, please see the following:

Canadian Centre on Substance Use & Addiction (CCSA)

Marijuana & Youth

The Canadian Centre on Substance Use & Addiction (CCSA) has engaged in extensive public consultation & research to determine how to address marijuana/cannabis use in youth.  In these efforts, CCSA has:

  • Conducted qualitative research, speaking with youth across the country to understand their views about marijuana. See the technical report, What Canadian Youth Think about Cannabis (2013) and Canadian Youth Perceptions on Cannabis (2017).
  • Developed a five​​-part marijuana research series, “Clearing the Smoke on Cannabis,” which includes a look at marijuana’s impact on cognitive functioning and mental health, respiratory functioning, pregnancy and driving. The series also reviews the use of marijuana for medical purposes.
  • Conducted a ​meta-analytic review of school-based prevention programs​ for marijuana use in an attempt to identify features that influenced program effectiveness.
  • Released The Effects of Cannabis Use during Adolescence​, the next installment of the Substance Abuse in Canada research series. This report gives parents​, teachers, healthcare providers and policy makers the opportunity to use the evidence in the report to develop and employ more effective youth drug use prevention and intervention programs.

Other key publications include:

Driving Under the Influence of Cannabis

In 2017, CCSA researchers determined that driving under the influence of cannabis (DUIC) costs an estimated $1 billion per year in Canada in the study “Estimating the Harms and Costs of Cannabis-Attributable Collisions in the Canadian Provinces.”  Cost was estimated by studying DUIC associated fatalities, injuries and damage to property in the Canadian provinces and territories in 2012. The highest costs are associated with fatalities, with young adults between the ages of 16–34 accounting for two-thirds of all DUIC fatalities.

Other key findings include: ​

  • In 2012, cannabis collisions in Canada resulted in an estimated 75 fatalities, 4,407 injuries and 7,794 victims of property damage only (PDO) collisions, with an estimated economic and social cost of approximately $1 billion.
  • The highest costs are associated with fatalities, accounting for more than 58% of the costs.
  • While less than fatalities, injury costs and costs related to PDO collisions are also substantial.
  • 16–34 year olds represent only 32% of the Canadian population, but 61% of the cannabis-attributable fatalities. This group also disproportionately represents 59% of the cannabis-attributable injuries and 68% of the people involved in cannabis-attributable PDO collisions. ​

This information has been summarized in the following publications:

  • Cost of Cannabis Collisions in Canadian Provinces in 2012 (infographic)
  • Collisions Attributable to Cannabis: Estimating the Harms & Costs in the Canadian Provinces (report at a glance)

Drug Free Kids Canada

Drug Free Kids Canada is a private sector, non-profit organization that creates and disseminates drug education and prevention messages with the help of their partners in advertising, research and media.

Working with Health Canada and the Canadian Centre on Substance Abuse, Drug Free Kids Canada developed a practical, easy-to-use guide for parents – “Cannabis Talk Kit: Know How to Talk with Your Teen” – that highlights the latest evidence on cannabis.