Double Trouble: Users Of Both Alcohol And Marijuana Take More Risks Behind The Wheel

Charlotte, N.C. (News Release) – People who use both alcohol and marijuana are some of the most dangerous drivers on the road – they are significantly more likely to speed, text, intentionally run red lights, and drive aggressively than those who don’t, according to data from the AAA Foundation for Traffic Safety. They also are far more likely to report driving under the influence of alcohol than those who consume only alcohol and not marijuana.

“Regardless of whether marijuana is legal or prescribed, driving under the influence of the drug is illegal and extremely dangerous,” said Tiffany Wright, Public Affairs Director, AAA – The Auto Club Group in the Carolinas. “Although some drivers think marijuana makes them a better driver, research shows it can inhibit concentration, slow reaction times, and cloud judgement. That judgement is even more compromised by a marijuana user who also drinks alcohol. It’s important that drivers know the risk that comes with these two drugs and never drive impaired.”

The AAA Foundation’s annual Traffic Safety Culture Index found that drivers who use both marijuana and alcohol were significantly more prone to driving under the influence of alcohol (Table 1) versus those who only drink alcohol but do not use marijuana. These motorists identified as someone who consumed alcohol and used marijuana 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 marijuana.

Driving Habits of Marijuana and Alcohol Users vs. Users of Alcohol only

Compared to alcohol-only users, drivers who admitted to using both were more likely to report such behaviors 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 marijuana 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. (See abstract)

Drug Use by the Numbers

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

According to government data, alcohol and marijuana 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 marijuana in the past year. As of today, 16 states and Washington, D.C., have legalized marijuana for recreational use. And in 2021, 15 state legislatures are considering medical or adult-use marijuana legalization bills.

AAA is committed to educating the public about the dangers of substance-impaired driving. Through AAA Foundation research, AAA is working to improve understanding of the topic and work collaboratively with safety stakeholders to reduce the impact of substance-impaired driving-related crashes.

Table 1. Prevalence of Self-Reported Impaired Driving Behaviors in Relation to Alcohol and Marijuana Use in a Sample of 2,710 U.S. Drivers, Weighted to Represent U.S. Driving Population Ages 16 and Older.

No Alcohol or Marijuana Use Alcohol Use Only Marijuana Use Only Both Alcohol and Marijuana Use
Total Respondents 1,434 1,036 103 137
DUI*—Alcohol N/A 14% N/A 39%
DUI—Marijuana N/A N/A 37% 52%
DUI—Prescription Drugs 4% 4% 14% 25%
Riding w/ intoxicated driver 5% 12% 13% 37%
Drowsy driving 21% 25% 22% 35%

Note: Percentages include responses of “a few times,” “fairly often,” or “regularly.”
*DUI refers to self-reported driving under the influence, not being charged with a DUI by law enforcement

Table 2. Prevalence of Self-Reported Risky Driving Behaviors in Relation to Alcohol and Marijuana Use in a Sample of 2,710 U.S. Drivers, Weighted to Represent U.S. Driving Population Ages 16 and Older.

No Alcohol or Marijuana Use Alcohol Use Only Marijuana Use Only Both Alcohol and Marijuana Use
Total Respondents 1,434 1,036 103 137
Read text b 24% 30% 31% 53%
Type/send text b 16% 21% 24% 40%
Speed—highway b 34% 43% 46% 55%
Speed—residential b 28% 35% 46% 55%
Running a red light a 28% 32% 38% 48%
Aggressive driving a 21% 28% 41% 52%
Drive w/o seatbelt b 11% 11% 16% 18%

a Percentages include responses of “a few times,” “fairly often,” or “regularly.”
b Percentages include responses of “just once,” “a few times,” “fairly often,” or “regularly.”