Impact of Cannabis Edibles Combined With Alcohol on Driving, Field Sobriety Performance, and Subjective Effects: A Within-Participant Crossover Trial.
JAMA network open May 1, 2026 C Austin Zamarripa, Spencer Lin, Mckenna Klausner et al.
Combining cannabis edibles with alcohol worsens driving impairment more than either substance alone. In a controlled experiment with 25 healthy adults who reported prior co-use, driving performance was significantly impaired under most active drug conditions, including 25 mg THC with alcohol at 0.05% breath alcohol concentration. The legal alcohol intoxication limit of 0.08% may be too high when cannabis has also been consumed. Standard field sobriety tests often failed to detect impairment that was evident in driving measures. The findings suggest a need for better impairment detection and policies that account for co-use.