Like alcohol, using cannabis inhibits your ability to drive safely. Even at low doses, using cannabis impairs a number of cognitive functions that affect your ability to operate a motorized vehicle or heavy machinery safely. In particular, cannabis affects perception, short-term memory, decision-making, and motor skills.

The Canadian Centre on Substance Use and Addiction has compiled a summary of evidence about Cannabis Use and Driving and has identified the following highlights:

  • After alcohol, cannabis is the most commonly detected substance among drivers who die in traffic crashes.
  • Driving under the influence of cannabis doubles the risk of being involved in a crash.
  • This risk increases even more when cannabis is used with alcohol. When used together, the effects of either drug may be more powerful, resulting in greater impairment than had either of the drugs been used alone.

    Due to the association between cannabis use and the harms around drug-impaired driving, it is recommended that people don’t drive or operate machinery within 6 hours of using cannabis.