Substance guides

Marijuana and driving: Why stoned driving is more dangerous than you think

Published November 18, 2024 · 7 min read · Updated April 2026

Reviewed for accuracy by licensed clinical professionals.

Marijuana impairs driving ability, and legalization has not changed the danger. THC-impaired driving increases crash risk by approximately 25-50%.

How marijuana impairs driving

Slowed reaction time. Impaired attention and concentration. Difficulty maintaining lane position (weaving). Impaired judgment of speed and distance. Reduced ability to handle unexpected events. These effects last 3-4 hours after smoking and longer after edibles.

The false confidence

Unlike alcohol, which tends to increase risk-taking, marijuana often makes users drive more slowly and cautiously. This creates a false sense of safety. But the impaired reaction time and attention mean they are less able to respond to hazards even if driving slowly.

Legal consequences

DUI laws apply to marijuana in all states. THC blood limits vary by state (some use 5 ng/mL, others use zero tolerance). Penalties include license suspension, fines, and potential jail time. A marijuana DUI carries the same legal weight as an alcohol DUI.

Authoritative sources

This article references guidelines from: SAMHSA · NIDA · ASAM

Frequently asked questions

Is it safe to drive high?

No. Marijuana impairs reaction time, attention, and hazard response. Crash risk increases 25-50%.

How long after smoking can I drive?

Wait at least 4-6 hours after smoking. After edibles, wait 6-8 hours or longer. If you feel any effects, do not drive.

Can I get a DUI for marijuana?

Yes. All states prohibit driving under the influence of marijuana. Penalties are equivalent to alcohol DUI.

Disclaimer: Informational only. Not medical advice. SAMHSA: 1-800-662-4357.