Driving While on Medical Marijuana: What Patients Need to Know

As more states legalize medical marijuana, there is growing concern about impaired driving among cannabis patients. It is important for every patient to understand how marijuana affects driving ability, the legal consequences of driving while impaired, and the recommended waiting periods before getting behind the wheel.

How Cannabis Impairs Driving

When a person uses marijuana, their attention span, reaction time, decision-making, and judgment are all affected. Cannabis impairs short-term memory and cognitive processing — resulting in slowed reflexes, confusion about surroundings, lack of coordination, and drowsiness. A person who drives within one hour of using cannabis has approximately twice the accident risk compared to a sober driver. Users may be up to six times more likely to be involved in a car accident while impaired.

Recommended Waiting Periods

Patients who have smoked or vaped marijuana should wait a minimum of four hours before driving. If cannabis was consumed as an edible, the recommended wait time is at least six hours due to the delayed onset and extended duration of effects. If a patient feels any euphoric or cognitive effects at all, driving should be avoided for a full eight hours. When in doubt, arrange alternative transportation.

Legal Consequences in Florida

Driving under the influence of marijuana can result in arrest and criminal charges in Florida. While there is no breathalyzer test for cannabis, law enforcement officers can make visual assessments and order drug tests. THC can be detected in urine for weeks after use, in blood for up to seven days, and in saliva for 24 hours. Consequences include fines, license suspension or revocation, jail time, and a permanent criminal record. Having a medical marijuana card does not grant legal immunity for impaired driving.