Skip to content

Impaired Driving

Impaired is Impaired

Cannabis, (medical and non-medical) and other drugs including prescribed drugs, over-the counter drugs and illegal drugs can impair your ability to drive safely and increases the risk of getting into a collision resulting in serious injury or death.

Drug impaired driving is the operation of a motor vehicle while under the influence of a drug. It includes anyone who operates a motor vehicle or has the care or control of a motor vehicle. This Includes snowmobiles, all-terrain vehicles (ATV’s), boats, trains and airplanes. It does not matter if the vehicle is being operated on a public road or on private property.

It is not clear how long after you use cannabis the impairment starts and how long it lasts. Depending on the method of use – smoking, vaping, drinking, eating or dabbing, the impairment may start shortly after use and last 2–6 or even 10 hours after.

How Cannabis Affects Your Ability to Drive

When you drive a vehicle, you need to be alert and focused. Consuming even small amounts of cannabis affects your ability to react and increases your chance of being in a crash. Cannabis impairs your ability to drive by:

  • Impairing psychomotor responses (impairing brain and body movement responses and coordination)
  • slowing reaction time
  • impairing short term memory and concentration
  • causing drivers to vary speed and to wander in the lane
  • reducing the ability to make decisions quickly or handle unexpected events

Cannabis affects everyone differently. Factors include:

  • driving experience
  • tolerance for cannabis (lowered response to a drug from repeated use)
  • the drug’s potency (concentration or strength of the THC, the chemical that is responsible for the feeling of being high)
  • how it was used  (smoking, vaping, drinking, eating or dabbing)

Combining cannabis and even a small amount of alcohol can greatly increase impairment.

You can learn more in the report,  Clearing the Smoke, Cannabis Use and Driving – An Update, from the Canadian Centre on Substance Use and Addiction, 2017 and Frequently asked Questions about pot and driving from the Canadian public health association updated March 2018.

Young Drivers are Most at Risk

Many car crashes involving teenagers are caused by inexperience and poor judgment. When these factors are put together with alcohol, cannabis or other drugs, the results can be tragic.

  • New drivers and people that don’t have much experience using cannabis are most at risk.
  • Young people are the largest group of drivers who die in crashes and test positive for drugs or alcohol.
  • For young drivers, driving high is more common than driving after drinking.
  • Young people are more likely to accept a ride from someone that is high than to drive high themselves.
  • The danger increases if the passengers are also high.  Impaired passengers can distract the driver or they may encourage risk-taking behaviour.

Ontario has a zero tolerance for both alcohol and drugs for young and novice drivers. You can learn more about Ontario laws and cannabis at the Ontario Ministry of Transportation, Impaired driving section and Alcohol and Drugs: Impaired is Impaired.

You have options:

  • Make sure you have a designated driver
  • Call a friend or loved one to pick you up
  • Take public transit
  • Call a cab or a rideshare service

Information for Parents

Young people are the largest group of drivers who die in crashes and later test positive for alcohol or drugs, and yet few parents discuss the risks of driving under the influence of drugs with their teenagers and fewer teens remember the messages.

Start a conversation with your child about impaired driving that includes a safety plan. You can find information about a safety plan in Strategies for Parents to Prevent Underage Drinking and You, Your Teen and Substance Use.

Commercial Drivers

Drivers requiring an A-F class licence cannot have any amount of cannabis or alcohol in their system. You can find more information about impaired driving on the Ministry of Transportation’s website.