Does marijuana impair driving the way alcohol does?


Yes and no. Large doses of marijuana can affect perception and psychomotor performance, changes that could impair driving ability. But in driving studies, marijuana produces little or no car-handling impairment – consistently less than produced by moderate doses of alcohol and many legal medications.

Mixing marijuana and alcohol together amplifies potential risks. Surveys show that when THC is detected in the blood of fatally injured drivers, alcohol is often detected as well.

It is never a good idea to get behind the wheel when intoxicated, even if just from marijuana alone.

For some people, marijuana may play a role in bad driving, but the overall rate of highway accidents does not appear to be significantly affected by marijuana’s widespread use. Also, people who frequently use marijuana appear to develop a tolerance to marijuana’s impairing effects.

Prevention Measures

Unfortunately, as a result of marijuana’s criminalization, harm prevention measures that exist for alcohol consumption – such as safe use guidelines, formal intoxication levels, designated driver education, and easily accessible information about how alcohol impacts physical and mental functioning – are not widely available for marijuana use.

In states where marijuana is legally controlled and regulated, public education about using marijuana safely, including not driving under the influence, is becoming more readily available.


What do you think?

People deserve accurate, non-judgmental information about marijuana and other drugs

In order to stay safe, we need to understand both the effects of drugs and the policies that surround them.

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Shelley's Story

Marijuana: The Facts

The Drug Policy Alliance (DPA) supports information and polices related to marijuana that are grounded in science, compassion, health and human rights. Safety is our top priority, especially when it comes to young people.
This booklet provides brief answers to some of the most commonly-asked questions about marijuana. We hope it will help you better understand this plant and its effects.