Prevalence of alcohol, cannabis, and simultaneous use among drivers in six states

Eichelberger, Angela H.
Insurance Institute for Highway Safety
September 2022

Objective: As more states legalize cannabis for recreational use, there is a need to understand how cannabis is used with other substances. Combining alcohol and cannabis at the same time is of particular concern, as this combination has been found to worsen driving performance and is associated with riskier behaviors.
Method: Telephone interviews were conducted with 3,045 adult drivers across six states (Connecticut, Delaware, New York, North Carolina, South Carolina, and Virginia) about their opinions and behaviors related to cannabis use, alcohol use, and driving.
Results: Self-reported substance use varied across states, with New York and Connecticut drivers reporting the highest proportions of past-year drinking (75%), cannabis use (29% and 26%), and simultaneous alcohol and cannabis use (15% and 14%). North Carolina drivers reported the lowest proportions of past-year drinking (65%) and past-year simultaneous alcohol and cannabis use (9%), and North Carolina and Virginia drivers reported the lowest proportion of past-year cannabis use (21%). Across the six states, past-year use of alcohol less than 2 hours before driving was more prevalent (17%–25%) than past-year use of cannabis less than 2 hours before driving (8%–11%), and the proportion who reported using both alcohol and cannabis less than 2 hours before driving ranged from 2% to 5%. Of the drivers who reported using a substance within the past year, 28% of alcohol users reported drinking less than 2 hours before driving; 41% of cannabis users reported using cannabis less than 2 hours before driving; and, among drivers who reported past-year simultaneous use, 33% reported using both alcohol and cannabis less than 2 hours before driving.
Conclusions: Due to the heightened risks associated with using alcohol and cannabis together, self-report surveys should include questions about simultaneous use of alcohol and cannabis in addition to questions about individual substances. An understanding of how substances are used either alone or in combination can better inform traffic safety programs..