A new study from the University of Saskatchewan has found that most young people who use cannabis crash in a driving simulation after eating cannabis edibles.
The research, which was completed in 2025, looked at people between the ages of 19 and 30 who use cannabis for fun. More than 75% of them crashed in the simulator after taking just one edible with THC, the part of cannabis that makes people feel high.
The study used a driving simulator to measure how well participants could drive. The simulator tracked things like how fast they reacted, how well they stayed in their lane, how fast they drove, and whether they crashed. Each person ate an edible with 10 milligrams of THC.
They were tested before taking the cannabis and again at 1.5, 2.5, 4, and 6 hours later. After the tests, the researchers made sure everyone got a cab ride home.
Dr. Alexander Crizzle, who led the study, said he was surprised by how quickly the cannabis started to affect people. Edibles usually take longer than smoking cannabis to cause effects, but in this case, the impact on driving came fast and lasted a long time.
Even at 2.5 and 4 hours, the drivers were still showing serious signs of being impaired. By six hours, the effects started to fade, but there were still some problems with driving.
During the tests, participants had trouble reacting quickly to things like pedestrians crossing the road or cars cutting them off. Many also had trouble staying in their lane. All of these problems added up to a lot of crashes.
Dr. Crizzle explained that the participants moved more slowly and were slower to make decisions. Even four hours after eating the edible, more than half of the participants still crashed the simulated car. The study also found that age and gender did not make a difference in how impaired someone became.
In Saskatchewan, there is a zero-tolerance rule for driving under the influence of drugs. This means drivers cannot have any cannabis in their system while driving. Crizzle said the results of this study support that rule. He said it is smart to keep this policy until there is more research available.
Cannabis is the second most common drug found in deadly crashes, right after alcohol. That’s why this kind of research is so important. It shows that even recreational cannabis users—people who don’t use it often—can still be seriously impaired.
Many people think edibles are safe to use, but this study proves that they can still affect your ability to drive safely for many hours.
The research was reviewed and approved by the USask Biomedical Research Ethics Board to make sure it was done safely and followed all national ethics rules.
This study helps fill a gap in knowledge about how cannabis affects driving. It also shows the public why it’s important to avoid driving after using cannabis—even if it was taken in edible form and even if several hours have passed.
If you care about cannabis, please read studies that what you need to know about cannabis and heart attack, and CBD from cannabis may help inhibit COVID-19 infection.
For more information about cannabis, please see recent studies that medical cannabis could help reduce depression, and results showing this stuff in cannabis may protect aging brain, treat Alzheimer’s.
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