What You Need to Know about Substance Use and Driving – Including Marijuana

"Each December, we recognize National Impaired Driving Prevention Month to raise awareness about the dangers of impaired driving and how to prevent impaired driving and related crashes, injuries, and deaths.

Driving while impaired by any substance is dangerous and illegal. The following substances can impair driving:

• Alcohol
• Marijuana
• Other illicit drugs like heroin, cocaine, methamphetamine, or hallucinogens
• Some prescription medications like opioids and antidepressants
• Some over-the-counter medications like sleep aids and allergy medicines

Fast Facts

• 11,654 people in the United States were killed in alcohol-impaired driving crashes in 2020—a 14% increase from 2019. That’s about 32 people every day or one person every 45 minutes.^[i]
• 7 million Americans reported driving under the influence of marijuana or other illicit drugs in 2020.^[ii]
• Alcohol and marijuana were the two most commonly reported substances involved in impaired driving in 2018, with 8% and 4.7% of the U.S. population aged ≥16 years reporting alcohol and marijuana respectively.^[iii]
• 1 in 8 high school student drivers reported driving after using marijuana at least once during the past month in 2017.^[iv]

How Does Substance Use Affect Driving?

How Marijuana Use Affects Driving

Driving is a complex task that requires your full attention to stay safe and alert. Marijuana use affects areas of the brain that control your body’s movements, balance, coordination, memory, and judgment. Marijuana use can impair important skills required for safe driving by:

• Slowing your reaction time and ability to make decisions
• Making it difficult to multitask
• Impairing coordination
• Distorting perception^{[i],[ii],[iii]}

If you are impaired, you cannot drive safely. It is illegal and dangerous to drive if you are impaired after using marijuana.

How Alcohol Affects Driving

The amount of alcohol in a person’s system is called blood alcohol concentration (BAC). Most states have set the legal BAC limit for driving at 0.08 grams of alcohol per deciliter (g/dL); the limit is 0.05g/dL in Utah.^[i] However, impairment starts at lower BAC levels, with even small amounts of alcohol affecting the ability to drive. The effects of alcohol use on driving include:

• Difficulty steering
• Reduced ability to respond to emergency driving situations
• Reduced ability to maintain lane position and brake appropriately
• Reduced ability to process what is happening on the road.."
  Impaired driving 

Tips for Driving Safely during the Holiday Season

"In the United States, motor vehicle crashes are a leading cause of death for people aged 1‒54,¹ and more than 36,000 people were killed in crashes in 2018.²

However, motor vehicle crash deaths and injuries can be prevented. Buckle up, drive sober, and stay safe on the road during the holiday season.

Learn safety tips for:

• All drivers
• Child passengers
• Teen drivers
• Older adult drivers

Safety Tips for All Drivers

• Do not drive when you are impaired by alcohol and/or drugs, and do not allow your family members or friends to drive while impaired. In 2018, alcohol-impaired driving contributed to more than 10,500 crash deaths.³ If you drink alcohol and/or use drugs, you should designate a sober driver, call a taxi, or use a ride share service.
• Avoid distractions while driving, such as using your cell phone to text, email, or access social media. Sending or reading a text takes your eyes off the road for at least five seconds. At 55 miles per hour, that is like driving the length of an entire football fieldexternal icon with your eyes closed. You cannot drive safely unless the task of driving has your full attention.
• Check the weather conditions before you head out on the road. Make sure to drive at a speed that is safe for road and weather conditions..."
  Holiday driving 

Drowsy Driving: Asleep at the Wheel

"The Drowsy Driving Problem

Drowsy driving is a major problem in the United States. The risk, danger, and often tragic results of drowsy driving are alarming. Drowsy driving is the dangerous combination of driving and sleepiness or fatigue. This usually happens when a driver has not slept enough, but it can also happen because of untreated sleep disorders, medications, drinking alcohol, or shift work.

No one knows the exact moment when sleep comes over their body. Falling asleep at the wheel is clearly dangerous, but being sleepy affects your ability to drive safely even if you don’t fall asleep. Drowsiness—

• Makes you less able to pay attention to the road.
• Slows reaction time if you have to brake or steer suddenly.
• Affects your ability to make good decisions.

Did You Know?

• An estimated 1 in 25 adult drivers (aged 18 or older) report having fallen asleep while driving in the previous 30 days.^1,2
• The National Highway Traffic Safety Administration estimates that drowsy driving was responsible for 72,000 crashes, 44,000 injuries, and 800 deaths in 2013.³ However, these numbers are underestimated, and up to 6,000 fatal crashes each year may be caused by drowsy drivers.^.."
  Drowsy driving

Drowsy Driving: Asleep at the Wheel

"Drive alert and stay unhurt. Learn the risks of drowsy driving and how to protect yourself.

The Drowsy Driving Problem

Drowsy driving is a major problem in the United States. The risk, danger, and often tragic results of drowsy driving are alarming. Drowsy driving is the dangerous combination of driving and sleepiness or fatigue. This usually happens when a driver has not slept enough, but it can also happen due to untreated sleep disorders, medications, drinking alcohol, or shift work.

No one knows the exact moment when sleep comes over their body. Falling asleep at the wheel is clearly dangerous, but being sleepy affects your ability to drive safely even if you don’t fall asleep. Drowsiness—

• Makes drivers less able to pay attention to the road.
• Slows reaction time if you have to brake or steer suddenly.
• Affects a driver’s ability to make good decisions.

Did You Know?

• An estimated 1 in 25 adult drivers (aged 18 years or older) report having fallen asleep while driving in the previous 30 days.^1,2
• The National Highway Traffic Safety Administration estimates that drowsy driving was responsible for 72,000 crashes, 44,000 injuries, and 800 deaths in 2013.³ However, these numbers are underestimated and up to 6,000 fatal crashes each year may be caused by drowsy drivers.^..."
  Drowsy driving

Safe Teen Driving

"Learning to drive is often considered a rite of passage for teenagers. But with the reward of being a new driver comes real risk. Car crashes are the leading cause of death for teens in the United States, taking the lives of six teens a day. CDC's Injury Center is committed to preventing teen crashes and related deaths and injuries.

CDC's study Parental Perceptions of Teen Driving: Restrictions, Worry and Influence  reveals that most parents report having rules and restrictions for their teen drivers, but only a small percentage formalize the rules and restrictions in a written parent-teen driving agreement. Parents worry less about their teen driver's safety during the newly licensed phase, when crash risk is high as compared to the learning phase. Implementing parent-teen driving agreements and updating existing agreements can assist families in keeping restrictions and expectations clear and ongoing as teens gain experience driving independently..."

Teen driving

Who Drives to Work? Commuting by Automobile in the United States: 2013

"The automobile has played a fundamental role in shaping where we live and how we get around. It has influenced the form and density of our communities and expanded the geographic range of daily travel. Nationally, the private automobile is the predominant form of transportation for work and other travel purposes.1 In 2013, about 86 percent of all workers commuted to work by private vehicle, either driving alone or carpooling (Figure 1). In recent years, the percentage of workers who commute by private vehicle remained relatively stable after decades of consistent increase. For several individual years since the mid-2000s, the average number of vehicle miles traveled in the United States has either increased at a slower pace than in previous decades or declined.2, 3, 4 Although such shifts in travel behavior are slight, they have captured attention because they represent a disruption in an unequivocal, decades-long pattern of increased automobile travel..."
Driving to work

Teen Drinking and Driving

" The percentage of teens in high school who drink and drive has decreased by more than half since 1991,* but more can be done. Nearly one million high school teens drank alcohol and got behind the wheel in 2011. Teen drivers are 3 times more likely than more experienced drivers to be in a fatal crash. Drinking any alcohol greatly increases this risk for teens..."
Teen Drinking and Driving

Safe and Healthy Winter

"Winter storms and cold temperatures can be hazardous, but if you plan ahead, you can stay safe and healthy. Prepare your home and cars. Keep emergency kits stocked. Be ready for power outages. Wear appropriate clothing. Check on children, the elderly and pets..."

CDC report shows about 112 million annual incidents of people drinking and driving

"Adults drank too much and got behind the wheel about 112 million times in 2010—that is almost 300,000 incidents of drinking and driving each day—according to a CDC Vital Signs study released today by the Centers for Disease Control and Prevention.

“The four million adults who drink and drive each year put everyone on the road at risk,” said CDC Director Thomas R. Frieden, M.D., M.P.H. “In fact, nearly 11,000 people are killed every year in crashes that involve an alcohol–impaired driver.”

For the study, CDC analyzed data from the 2010 Behavioral Risk Factor Surveillance System Survey.

The study also found that:

Men were responsible for 81 percent of drinking and driving in 2010.

Young men, ages 21–34, made up only 11 percent of the U.S. population in 2010, yet were responsible for 32 percent of all episodes of drinking and driving.

Eighty–five percent of drinking and driving episodes were reported by people who also reported binge drinking. Binge drinking means five or more drinks for men or four or more drinks for women during a short period of time..."