Drug-Impaired Driving


Prescription drugs, over-the-counter medications, and illegal drugs may cause impairment alone or in combination with each other and/or with alcohol. In every State and the District of Columbia, impaired driving is illegal. Whether by drugs—legal or illegal—alcohol, or a combination of both drugs and alcohol, impaired driving puts the driver, their passengers, and other road users at risk. In NHTSA’s National Roadside Survey conducted in 2013-2014, 20 percent of drivers surveyed tested positive for potentially impairing drugs. Let’s work together to share this life-saving message: Impaired driving is illegal and deadly.

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The Issue

Drug-Impaired-Driving Trends

While we’ve long studied and understood the dangers involving drunk driving, we are still researching and learning about the effects of drugs on driving. Meanwhile, it has become an increasing public and governmental concern in the United States.

The 2013-2014 Roadside Survey of Alcohol and Drug Use by Drivers found an increase in the number of drivers testing positive for marijuana and other drugs that can impair driving skills compared to the 2007 survey findings. In the 2013-2014 survey, nearly one in four drivers tested positive for at least one drug that could potentially affect safe driving skills.

Drug-impaired driving is an important safety issue that NHTSA continues to research. The agency is working to develop new knowledge on how drugs affect driving, to grow new and enhance existing programs to reduce drug-impaired driving.

The Issue

How Marijuana Affects Driving

In recent years, State actions to legalize the use of marijuana for medical and recreational use have increased concern over potential risks of driving impaired by marijuana. Other than alcohol, it is the drug that is most frequently detected in drivers’ systems after a vehicle crash, as well as the general driving population (Compton & Berning, 2017; Kelley-Baker et al., 2017; Lacey et al., 2009; Walsh et al., 2005).

NHTSA’s Crash Risk Study, the largest of its kind ever conducted, assessed whether marijuana use by drivers is associated with greater risk of crashes. The survey found that marijuana users are more likely to be involved in crashes, but that the increased risk may be due in part because marijuana users are more likely to be in groups at higher risk of crashes. In particular, marijuana users are more likely to be young men – a group already at high risk. NHTSA is conducting another crash risk study, however; this time, only serious injury and fatal crashes will be investigated.

We know that marijuana can be dangerous when combined with driving. Studies show that marijuana impairs psychomotor skills, lane tracking, and cognitive functions (Robbe et al., 1993; Moskowitz, 1995; Hartman & Huestis, 2013), but it is still unclear the extent to which it contributes to the occurrence of vehicle crashes. Some studies have attempted to estimate the risk of driving after marijuana use (Li et al., 2012; Asbridge et al., 2012), but these remain inconclusive in terms of predicting real-world crash risk.

NHTSA In Action

NHTSA is dedicated to eliminating risky behaviors on our nation’s roads

Drug-Impaired Driving Summit Event Information

On Thursday, March 15, NHTSA is hosting a public meeting to kick off its new Drug-Impaired Driving Initiative. The summit will bring together key stakeholders — including safety partners; state and local elected officials; data and policy experts; law enforcement and criminal justice professionals; toxicologists and drug recognition experts — to join the U.S. DOT in setting a course of action and taking measurable steps to address the nation’s drug-impaired-driving problem. The summit will explore best practices for educating the public on the overall risk of drug-impaired driving; collecting consistent data and tracking Driving Under the Influence of Drugs (DUID) citations; testing and measuring driver impairment levels; and enforcing drug-impaired driving laws.

“Nobody can solve drug-impaired driving alone, but by sharing best practices we can begin to save lives today – we cannot afford to wait,” said Heidi King, NHTSA Deputy Administrator. “And by advancing the science and the data, we can address this problem for our communities in the future.”

To register for the summit, please click here. Space at this meeting is limited. The meeting will also be available for live public viewing. The meeting will start at 9 a.m. ET and continue until 4 p.m. ET.

Ideas, concerns, and thoughts

NHTSA wants you to join in the conversation about drug-impaired driving. Share your thoughts, concerns, ideas to us in an email. We'll summarize and add them to the appropriate idea board from the meeting.



Search for more resources

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Title Type Audience Date Language
NHTSA Launches Drug-Impaired Driving Initiative and Announces March 15 Summit
Press Release 01/25/2018
Marijuana-Impaired Driving - A Report to Congress PDF, 1.06 MB
Document Car Owners 07/01/2017
WA-roadside-survey-data-dictionary PDF, 279.1 KB
Document Advocacy Groups 06/23/2017
WA-roadside-survey-data-dta ZIP, 769.68 KB
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