Cannabis Edibles Impair Driving Even Below Legal THC Limits

published on September 17, 2026 by Marilynn Larkin in Medscape

Cannabis edibles dose-dependently impair simulated driving performance hours after ingestion at blood concentrations of delta-9-tetrahydrocannabinol (THC) below limits commonly used for roadside enforcement, new data suggest.

“We were surprised to see that the level of THC in the blood was so low compared with smoked cannabis,” Bernard Le Foll, MD, PhD, a senior scientist at the Centre for Addiction and Mental Health (CAMH) in Toronto, told Medscape News Canada. “Many people will show impairment in their driving ability while being below the limit that’s used by law enforcement for impairment assessment.”…