• Posted May 6, 2026

Edibles + Alcohol Combo Poses Driving Risks Missed by Sobriety Tests

A new study is raising questions about what roadside sobriety tests actually detect -- and what they might miss.

Researchers at Johns Hopkins Medicine, with support from the National Institute on Drug Abuse, studied how marijuana edibles and alcohol affect driving performance.

"We designed this study because people are increasingly co-using alcohol with edible cannabis products, yet controlled research has largely focused on smoked cannabis," said principal investigator Tory Spindle, an associate professor of psychiatry and behavioral sciences at Johns Hopkins University School of Medicine in Baltimore.

During multiple experiments, 25 healthy adults between 21 and 55 years of age, were given either pot-infused brownies, alcohol, both drugs, or placebos. For each session, participants were asked to complete simulated driving tasks and standard field sobriety tests.

The first major finding: Combining edibles with alcohol caused greater and longer-lasting driving impairment than did either substance alone. Increased impairment occurred even at alcohol levels below the legal limit of 0.08%.

Researchers say the interaction of these two drugs may be synergistic, meaning the combined effects can exceed the impact of each drug individually.

The second major finding: Cannabis edibles -- either alone or combined with alcohol -- did not significantly impair performance on standard field sobriety tests. Participants were only identified as intoxicated at the highest alcohol dose tested.

"This is the first controlled study to examine how cannabis edibles and alcohol interact, despite their growing combined use," Spindle said.

The authors said these findings highlight an urgent need for public education on the risks of combined drug use and for improved roadside impairment detection methods.

The findings were published May 1 in JAMA Network Open.

More information

The Colorado Department of Transportation has more on mixing cannabis and alcohol and driving.

SOURCE: HealthDay TV, May 6, 2026