THC, the psychoactive substance in hashish, marijuana and other cannabis products, can be detected in the blood for up to 24 hours after single use. In cases of regular or heavy use, THC can be detected in the blood for up to two weeks after the last intake.

Hash, marijuana, and other cannabis products can cause hallucinations, a distorted perception of reality, and increased overconfidence. They impair reaction time, spatial orientation, and the ability to register and process external stimuli. Cannabis also has an acute negative effect on coordination, which significantly impairs driving ability and increases the risk of traffic accidents.

In Sweden there is a zero limit for narcotic-classified substances in the blood of drivers. Both illegal and legal drugs, as well as certain medications, are regarded as narcotics.

The zero limit for narcotics means that it is prohibited to drive with narcotics in the blood, regardless of whether you are affected or not. Many drugs remain in the blood for a long time – for example, hashish and marijuana can remain in the blood for up to two months – which means that someone trying a drug at a party may be found guilty of driving under the influence of narcotics several weeks later.

The only exception to this rule is for narcotic medications that have been taken according to a doctor's prescription. However, remember that you are not allowed to drive if you are affected by the medication.

Read more about narcotics combined with driving