Study: Joint Alcohol/Cannabis Users are Riskier Drivers

As 4/20 looms, new research sheds light on dangerous driving.

Traffic Safety

DENVER (April 19, 2021) - Those who choose to use both alcohol and cannabis are among the most dangerous drivers on the road - even when they use the substances separately. That's the takeaway from new AAA research that found people who drink and get high are more likely to speed, text, intentionally run red lights, and drive aggressively than those who don't.

"Historically, Coloradans have had a thoughtful approach to cannabis use, and many who choose to use the drug would never drive high," said Skyler McKinley, regional director of public affairs for AAA. "Still, some drivers mistakenly believe that high driving is safe driving, even though the research is clear that cannabis can inhibit concentration, slow reaction times, and cloud judgment. The consequences can be even worse for cannabis users who also drink alcohol." McKinley was the founding deputy director of Colorado's Office of Marijuana Coordination, the cabinet-level agency charged with implementing the recreational cannabis marketplace, in 2014 and 2015. 

The AAA Foundation for Traffic Safety's annual Traffic Safety Culture Index found that drivers who use both cannabis and alcohol were significantly more prone to driving under the influence of alcohol as compared to those who only drink alcohol but do not use cannabis. 

These motorists identified as someone who consumed alcohol and used cannabis in the past 30 days, and in some cases, they may have used both at the same time. They also engage in various other dangerous driving behaviors far more than drivers who consume either just alcohol or abstain from either drinking alcohol or using cannabis.

Driving Habits of Cannabis and Alcohol Users vs. Users of Alcohol Only

Compared to alcohol-only users, drivers who admitted to using both drugs were more likely to report such behavior as: 

• Speeding on residential streets (55%) vs. alcohol-only (35%)
• Aggressive driving (52%) vs. alcohol-only (28%)
• Intentional red-light running (48%) vs alcohol-only (32%)
• Texting while driving (40%) vs. alcohol-only (21%)

Unsurprisingly, the study found drivers who neither drink alcohol nor use cannabis were considerably less likely to engage in the sorts of risky driving behaviors examined. This Foundation research was published in January 2021 in the peer-reviewed journal Transportation Research Record

Drug Use by the Numbers

Previous AAA research suggests that users who drive high are at least twice as likely to be involved in a crash.

All told, alcohol and cannabis are the most widely used drugs in the United States - 139.8 million people aged 12 or older reported drinking alcohol in the past month, and 43.5 million reported using cannabis in the past year. As of today, 16 states and Washington, D.C., have legalized cannabis for recreational use. What's more, in 2021, 15 additional state legislatures are considering medical or adult-use cannabis legalization bills.

"Fundamentally, choosing to use alcohol or cannabis is just that - a personal choice. While there are safe ways to use both drugs, there is no safe way to drive under the influence of either," McKinley said. "Never, never, never drive impaired."

About AAA - The Auto Club Group
AAA Colorado is a proud part of The Auto Club Group (ACG), the second-largest AAA club in North America with more than 14 million members across 14 U.S. states, the province of Quebec and two U.S. territories. ACG and its affiliates provide members with roadside assistance, insurance products, banking and financial services, travel offerings and more. ACG belongs to the national AAA federation with more than 60 million members in the United States and Canada. AAA's mission is to protect and advance freedom of mobility and improve traffic safety. For more information, get the AAA Mobile app, visit, and follow us on Facebook, Twitter and LinkedIn.