This post was co-written with Candace Lightner, President of We Save Lives.org and founder of MADD, Mothers Against Drunk Drivers.

Every time you get on the road, chances are good that you’re seeing drivers of all ages under the influence. Not necessarily on alcohol, but on drugs—both illicit and perfectly legal. Although the dangers of drinking and driving are well-known, the effect of drugs is less publicized—and potentially far more lethal, given the numbers.

Consider these sobering facts:

  • Car crashes are the number one cause of death for teens.
  • Every day, on average, 2,500 teens use prescription drugs to get high for the first time, according to the US Drug Enforcement Administration.
  • According to a 2011 National Institute on Drug Abuse Survey, nearly 1 in 6 high school seniors who responded reported that, within the past 2 weeks, they had driven a motor vehicle after using an illicit drug or drinking heavily.
  • In the same survey, nearly 1 in 4 had recently ridden in a car with such a driver. Altogether 28 percent had put themselves at risk in the past 2 weeks by being in a vehicle whose driver had been using marijuana or another illicit drug, or had drunk 5 or more alcoholic drinks. These rates had all risen nearly 20 percent in only 4 years, due almost entirely to an increase in driving after smoking marijuana.
  • According to the National Institute on Drug Abuse’s 2014 Monitoring the Future survey, which measures alcohol and drug use among over 41,000 American 8th, 10th, and 12th graders, 27 percent of all survey participants used illicit drugs, 6 percent had abused prescription and over-the-counter drugs, and over 37 percent of high-school seniors had ingested alcohol in the previous year.

So why do teens use drugs? For the same reasons that adults often do—to regulate their mood, stay alert, lose weight, cope with everyday life, or just have fun. Teens abuse a variety of drugs, such as alcohol; prescription medications; inhalants; over-the-counter cough, cold, and sleep medications; marijuana, cocaine, opiates, heroin, PCP, and designer drugs such as Ecstasy.

How do these drugs affect driving? Many drugs have similar effects on our cognitive and motor skills as alcohol, by impairing judgment, concentration, vision, and sense of risk-taking, which can lead to overconfidence, hallucinations, and unpredictable behavior. This turns especially deadly if a person ingests more than one drug at a time or also consumes alcohol, since drug interactions vary widely by individual.

Driving under the influence of marijuana can be just as dangerous as driving under the influence of other drugs. Most teens (and adults) think they drive more carefully after they use marijuana. But they don’t—using marijuana nearly doubles the risk of a vehicle collision, even though drivers don’t regard cannabis use to be as detrimental as alcohol.

If you need more proof, read the story of the young teenager from New York City who killed four of his friends while driving high. The fact that he was traveling at more than 100 miles an hour when he crashed into a tree hardly bodes well for driving more carefully. This young man will spend the next 5 to 15 years incarcerated as a result of his dangerous and deadly behavior. The victims’ families will spend a lifetime mourning their loved ones.

What’s more, teens who regularly use marijuana are more likely to become addicted to it than adults. And research is finding that even occasional marijuana use in adolescence may actually change brain function and lower IQ.

Why is drugged driving so dangerous for teens? Drugged driving is lethal for any age, but especially so for teens aged 16 to 19, for whom vehicle collisions are already the leading cause of death. Their natural overconfidence, feelings of invincibility, lack of experience, and vulnerability to social pressure is a potent cocktail for tragedy.

Which brings us to the hard questions—what can we do to help teens drive responsibly, as parents, friends, family, classmates, teachers, physicians, and counselors?

  • Be a good role model. Do your teens see you take illegal drugs or prescription medications, then get behind the wheel? We are role models for our children, and we cannot expect them to act differently than we do.
  • Hold off on letting them get their license until you are sure they are mature and responsible enough to handle a two-ton weapon.
  • Educate them about the law and the penalties. It is against the law to drive under the influence of drugs and not just alcohol, even in a state where marijuana is allowed. These penalties can be steep, so let your teen know this isn’t a minor offense.
  • Let them know that drugged driving is as dangerous as drinking and driving. Many teens believe that it is safer to drive under the influence of drugs than alcohol.
  • Emphasize that drugged driving is a choice. If they make the mistake of taking drugs or if they have a drug problem, they need to refrain from driving—or face the consequences.
  • Offer to drive them home without penalty if they ever feel that driving is a risk for themselves or if riding with someone else is dangerous.
  • Ask them to take the pledge to drive alcohol- and substance-free.
  • Take the car keys away if you suspect irresponsible behavior. Remember, you are the parent, and you have a lot more control than you think. It’s up to you to leverage that power and remind your child that driving is a privilege, not a right. Emphasize that you care about their safety and that of other innocent drivers on the road.
  • You can never start the discussion too early. Many parents feel awkward talking to their children about drug use. But the average age of first marijuana use is 14, and alcohol use can start before the age of 12. Kids have easier access than ever to both legal and illegal drugs from classmates and family members. Broaching the subject as early as kindergarten and having regular, friendly conversations about it sends the message that you care—and that you’re keeping an eye on them.
  • Attend a drug-prevention event. Many law enforcement agencies put on free or low-cost community seminars to increase public awareness of drugged driving as well as offer prevention tips. Ask your local police or school about such events.
  • Stay involved. As much as adolescents tend to push adults away, letting them know that you are interested and staying active in their lives is crucial. Don’t be afraid to ask questions and to get nosy about who they hang out with (or ride in other vehicles with), even if you get yelled at. Teens are often more grateful for adult guidance and involvement than they let on.

We can never protect our children 100 percent, and when your teen starts driving, sleepless nights can become a habit. However, there are things we can do as parents to help keep our children safe; the most important is to show them how much we love them by providing boundaries and guidance as they continue their journey into adulthood.