Marijuana and driving

Originally Published: February 18, 2000 - Last Updated / Reviewed On: April 28, 2011
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Dear Alice,

I was wondering if you had anything about marijuana and driving.

Thanks. J

Dear J.,

Just about everyone has heard, "Don't Drink and Drive" and "Friends Don't Let Friends Drive Drunk." But not as many realize that there are many dangers associated with getting behind the wheel of a car (or bus, train, or plane) while high on marijuana.

Pot use impairs one's ability to reason and make decisions, and slows reaction time. In addition, motor skills and visual tracking ability are diminished. Studies have shown that smoking just one marijuana joint reduces reaction time by 41 percent, while two joints reduces it by 63 percent. In 2001, almost 40,000 high school seniors in the United States reported that they got into car accidents while driving high. In another study, 33 percent of people pulled over for reckless driving tested positive for mariiuana use. Driving while high may also not be safe because users usually feel a bit tired and have difficulty concentrating after smoking. Sometimes people experience anxiety and/or visual, perception, and time distortions, none of which would help with navigating a vehicle on a road, or even in the driveway. Also, pot impairs memory formation, so if someone is given directions of where to drive while high, there's a chance that s/he won't quite remember how to get from point A to point B once the trip has begun.

Keep in mind that many other drugs — whether they be legal or not, recreational or prescription — affect cognition and motor skills. In fact, 18 percent of deaths caused by motor vehicle accidents are due to drug use (which does not include alcohol). To ride the road to safety, you should avoid operating heavy machinery (cars, tractors, amusement park rides, etc.) until you've checked into the effects of a drug you're taking on your ability to think straight and move smoothly.

For more information, check out the "Marijuana" category in under the Alcohol, Nicotine, and Other Drugs section in Alice's archives.