Anyone who possesses, consumes or even sells illegal narcotics is liable to prosecution. The substances included in the list of illegal narcotics are listed under the following link: Ordinance of the FDHA on the Schedules of Narcotics, Psychotropic Substances, Precursors and Auxiliary Chemicals.
Cannabis
Cannabis is considered an illegal narcotic in Switzerland, but enjoys a special status:
-Cannabis is only illegal if the THC content is above 1%. Products such as CBD are therefore not illegal.
-Possession of up to 10 grams of cannabis with more than 1% THC for personal use is not punishable.
-However, if consumption is observed by the police, it can be punished with a fine of 100 francs.
You can find more information on this topic at: Cannabis - What the law says in Switzerland
The times given below are for guidance only and can vary greatly from person to person.
Hair test
The longer the hair, the longer the consumption can be determined. For example, if the hair is 12 cm long, it is possible to draw conclusions about one year's consumption. If the hair is not cut, substances are theoretically always detectable.
Saliva test
Since 2005 saliva tests calibrated for the most common substances have been used for roadside checks. If the test is positive, a blood sample is always taken. In order for the police to carry out this test, there must be a so-called suspicion of narcotics consumption (in contrast to the alcohol test, which can also be carried out without suspicion).