A new Canadian study is raising red flags about the impact of edible cannabis on young drivers, pointing to significant impairment that may go unnoticed until motorists are already on the road. The research, funded by CAA and conducted by the University of Saskatchewan, suggests reaction time, lane discipline and speed control are all compromised after consuming THC-infused edibles — with the most pronounced effects emerging about 90 minutes after use.
The findings add to growing concerns about cannabis-impaired driving in Ontario, where nearly one in five motorists admit to driving high, according to a recent CAA South Central Ontario (CAA SCO) survey.
“This study marks an important first step in understanding how cannabis edibles impact driving performance,” says Michael Stewart, Community Relations Consultant for CAA South Central Ontario. “Too often, decisions about whether someone is fit to drive are made in the moment, relying on judgment rather than evidence. Cannabis impairment studies like this are essential. Each one brings new learnings that help us refine our approach and ensure that safety is never left to chance.”
Impairment often sets in after drivers are already on the road
The University of Saskatchewan study examined 50 drivers aged 19 to 30 — a demographic with the highest crash rates in Canada and a well-documented tendency toward riskier driving behaviour. Participants consumed a 10 mg THC edible before completing multiple driving simulations, resulting in 250 assessments across a range of realistic scenarios.
Researchers found the impairment peak at roughly 90 minutes after consumption. Because edibles can take longer to take effect than smoked cannabis, users may begin driving before feeling any noticeable change in alertness or coordination.
Despite the demonstrated impacts on performance, only four per cent of study participants said they felt safe to drive 90 minutes after consuming an edible.
Confidence out of step with actual risk
CAA’s broader research indicates a sharp disconnect between drivers’ perceptions and the reality of cannabis impairment. A survey of 1,510 Ontario drivers found that while the share of people who admit to driving after cannabis use — nearly 20 per cent — has held steady, confidence in driving abilities while high has risen sharply. According to the findings, 78 per cent of cannabis-impaired drivers now believe they drive competently under the influence, a 13-point increase since 2021.
More than one-third of those who admitted to cannabis-impaired driving also acknowledged feeling high behind the wheel, relying on their own interpretation of impairment symptoms such as tiredness, slowed reactions or brain fog.
“This misplaced confidence can lead to dangerous decisions, increasing the risk of collisions and endangering road users,” adds Stewart. “We must recognize that getting behind the wheel is not just a personal choice it’s a responsibility that affects the safety of everyone on our roads.”
Rise in poly-substance use intensifies safety concerns
Alongside the findings on edibles, the research highlights a growing trend of poly-use — consuming cannabis in combination with other substances. More than half of survey respondents (57 per cent) reported using cannabis with other drugs or alcohol. While alcohol remains the most common pairing, substances such as painkillers, psilocybin, ecstasy and MDMA are also on the rise.
Combining substances can significantly amplify impairment, creating additional challenges for law-enforcement agencies and policy-makers working to improve roadway safety. CAA says the trend underscores the need for stronger education efforts ahead of the holiday season.
“While we’re all aware that alcohol-impaired driving can be dangerous, we should also take the same attitude towards cannabis-impaired driving,” says Stewart. “With the holiday season coming up, cannabis can be consumed legally and responsibly but should never be used when driving.”
CAA urges drivers to plan ahead
CAA SCO is calling on motorists who choose to consume cannabis, alcohol or other drugs to make alternate transportation plans. The organization recommends arranging a designated driver, using public transit or calling a rideshare service to avoid impaired driving.
The organization, which represents more than 2.6 million members in South Central Ontario, has long advocated for evidence-based road-safety initiatives, working with police, governments and community groups to promote safe driving behaviour.
Study methodology
The CAA SCO survey was conducted online by DIG Insights between June 27 and July 14, 2025, sampling 1,510 Ontario drivers aged 19 and older. The margin of error is ±2 per cent at a 95 per cent confidence level.
The University of Saskatchewan study involved 50 young adult drivers who completed simulations after consuming a 10 mg THC edible, producing 250 total assessments of driving performance.
