Research has shown that marijuana can negatively affect driving ability by increasing lane weaving, slowing reaction time, impairing depth perception, decreasing coordination, and altering attention to the road. These effects can last for hours after use.
Method of use matters!
Smoking or vaping cannabis can produce effects within seconds or minutes, with peak impairment typically occurring about 30 minutes after use. Cannabis can impair judgment, coordination, reaction time, and driving ability for up to 12 hours after use.
Edibles and cannabis-infused drinks can cause impairment for even longer because THC is absorbed more slowly and unpredictably through digestion. Once processed by the liver, THC converts into a more potent form that can produce stronger and longer-lasting effects. Depending on the dose and individual factors, edibles may impair judgment, coordination, reaction time, and driving ability for 12–24 hours after consumption.
Edibles can take anywhere from 30 minutes to 2 hours to take effect, which may lead someone to believe they are not impaired and consume more before the full effects are felt. As the THC continues to absorb, impairment can increase significantly over time.
A review of multiple studies by Rogeberg & Elvik (2016) found that drivers with THC detected in their blood, saliva, or urine had 20–30% greater odds of being involved in a motor vehicle crash. Even when someone feels “fine,” cannabis can impair reaction time, coordination, attention, and decision-making in critical moments behind the wheel.
A split second can change lives forever. If you choose to use cannabis, plan ahead for a safe ride before you get behind the wheel. In Montana, driving under the influence of cannabis is illegal and is referred to as DUIC (Driving Under the Influence of Cannabis).
Friends Don't Let Friends Drive High
Sometimes we’re in situations where someone in our lives is making the riskier choice to use cannabis and then drive. What can you do in that situation and what can you say to stay safe?
- Plan ahead
- Stay informed
- Don’t wait until that person is high to have the conversation.
- Talk beforehand.
- Don’t ride with them. Find an alternative ride.