Mixing Edible Cannabis and Alcohol May Impair Driving More Than Scientists Expected

Key Points:

• A Johns Hopkins Medicine study found that combining cannabis edibles with alcohol produces stronger and longer-lasting driving impairment than using either substance alone, with effects potentially synergistic rather than merely additive.
• Standard field sobriety tests failed to detect impairment caused by cannabis, whether used alone or with alcohol, highlighting limitations in current roadside testing methods.
• The legal alcohol intoxication limit of 0.08% breath alcohol concentration (BrAC) may be insufficient to protect against driving impairment when cannabis edibles and alcohol are combined.
• The study involved controlled experimental sessions with healthy adult participants who received cannabis-infused brownies, alcohol, or placebos, followed by simulated driving and performance assessments over several hours.
• Researchers call for improved public health messaging, policy adjustments, and development of better detection tools to address the increased risks of co-using cannabis edibles and alcohol while driving.