Weed, THC, Car Crashes, and Fatalities
Research provides alarming evidence about driving under the influence of THC
By Mark S Gold
Published by Psychology Today on October 11, 2025
Key points
• An American College of Surgeons coroner study showed 42% of drivers in fatal crashes tested positive for THC.
• THC harms driving, impeding coordination, visual function, and attention for several hours after consumption.
• High-THC cannabis, vaping THC, and use with other drugs or alcohol make driving even more dangerous.
Sometimes marijuana can kill, not by overdose, but when people drive under the influence of THC. Recent research analyzed coroner records in Montgomery County, Ohio, from January 2019 through September 2024 to identify THC, the psychoactive drug derived from cannabis, in drivers in fatal crashes. Shockingly, close to half (42%) of the drivers killed in crashes tested positive for THC in the blood.
