Cannabis consumption by car drivers
Far greater risk of accidents
Drivers need to know what they must consider if they have smoked a joint. Thomas Wagner, Head of Driver Aptitude Assessment at DEKRA, answers the most important questions. The effects of cannabis differ greatly from person to person, but one thing is certain: The risk of accidents after consuming cannabis increases by between 25 and 166 percent.
Among young drivers under the age of 25, the risk has tripled. The combination of cannabis and alcohol is extremely dangerous, resulting in problems with complex tasks, concentration, and reaction – and in some cases in a greater willingness to take risks.
What are the limits for drivers?
The german law, for example, prohibits anyone with 3.5 nanograms or more of tetrahydrocannabiol (THC) – one of the active substances in cannabis – from using a vehicle. Violations will result in a fine of 500 euros; repeat offenders can be fined up to 1,500 euros and required to take a driver aptitude test. It is important to bear in mind that drinking alcohol is prohibited in conjunction with the consumption of cannabis. Also, all drivers under the age of 21 and probationary drivers are prohibited from driving under the influence of cannabis. A zero cannabis limit applies to them.
When can I drive again after smoking a joint?
We recommend that occasional cannabis users wait around 12 hours before driving again. Even if a driver is below the limit, they could still face prosecution if they have an accident or are considered to have driven unsafely. If the amount of THC in the “weed” is unknown and could be higher, drivers should wait 24 hours before taking the wheel again.
What about regular users?
So far, there have been no detailed studies of the effects of more regular consumption, i.e., on several weekdays and at weekends. The body is no longer able to break down all the THC. Smoking a fresh joint adds more THC to what has already accumulated in the fatty tissue, increasing the concentration in the body. We therefore recommend taking a break from smoking for as long as the preceding period of regular and continuous consumption. After consuming moderate individual amounts, we assume that it will normally take three to five days for the level of THC to fall below the limit of 3.5 nanograms.
What about more frequent cannabis consumption?
People who use cannabis almost daily may no longer drive and must wait for several weeks before they do. Chronic, daily, or near-daily consumption of large amounts or regular and excessive consumption are indicative of addiction, and this type of user may no longer drive at all. They should only consider doing so again after a prolonged period of abstinence coupled with addiction counseling or therapy.