Use of illegal drugs or misuse of prescription drugs can make driving unsafe — just like driving after drinking alcohol. Drugged driving puts the driver, passengers, and others who share the road at risk.

The effects of specific drugs differ depending on how they act in the brain. For example, marijuana can slow reaction time, impair judgment of time and distance, and decrease coordination. Drivers who have used cocaine or methamphetamine can be aggressive and reckless when driving. Certain kinds of sedatives, called benzodiazepines, can cause dizziness and drowsiness. All of these impairments can lead to vehicle crashes.

Research studies have shown negative effects of marijuana on drivers, including an increase in lane weaving, poor reaction time, and altered attention to the road. Use of alcohol with marijuana increased driver impairment. It is difficult to determine how specific drugs affect driving because people tend to mix various substances, but we do know that even small amounts of some drugs can have a measurable effect.

According to the 2014 National Survey of Drug Use and Health (NSDUH), 10 million people reported driving under the influence of illicit drugs during the year prior to being surveyed; men are more likely than women to drive under the influence of drugs or alcohol; and a higher percentage of young adults aged 18 to 25 drive after taking drugs or drinking than do adults 26 or older. After alcohol, marijuana is the drug most often found in the blood of drivers involved in crashes. Along with marijuana, prescription drugs are also commonly linked to drugged-driving crashes. The most common prescription drugs found were pain relievers.

It is hard to measure how many crashes are caused by drugged driving because a good roadside test of drug levels in the body doesn’t yet exist, police don’t usually test for drugs if drivers have reached an illegal blood alcohol level because there is already enough evidence for a DUI charge, and many drivers who cause crashes are found to have both drugs and alcohol, or more than one drug in their system, making it hard to know which substance had the greater effect.

Teen drivers are less experienced and are more likely than older drivers to underestimate or not recognize dangerous situations. They are also more likely to speed and allow less distance between vehicles. When lack of driving experience is combined with drug use, the results can be tragic. Car crashes are the leading cause of death among you people aged 16 to 19 years.

A 2011 survey of middle and high school students showed that, in the two weeks before the survey, 12 percent of high school seniors had driven after using marijuana, compared to about 9 percent who had driven after drinking alcohol. A study of college students with access to a car found that 1 in 6 had driven under the influence of a drug other than alcohol at least once in the past year.

Drugged driving puts people at a higher risk for crashes, creating a significant public health and public safety threat. Help prevent your child from getting behind the wheel of a car, or riding with an impaired driver by discussing the dangers and consequences. For more information on the effects of drugged driving and how to begin the conversation with your child, visit these websites: www.usacbrowncounty.org; www.drugabuse.gov; www.nih.gov; www.hhs.gov.

(Source: NIDA, 2016)