Interest in cannabis-based medicines has risen importantly in recent years due to the wide range of potential uses. On the other hand, delta-9-tetrahydrocannabinol (THC) impairs driving performance and other safety-sensitive tasks. Under the Swiss law, use of cannabis with a THC content of at least 1% is generally prohibited. However, the Swiss Parliament has decided to lift the ban on cannabis-based medicines from 1 August 2022. Hence, exceptional authorisation from the Federal Office of Public Health is no longer required for cannabis-based medicine prescription. Accordingly, general practitioners may prescribe these medicines (e.g. 'magistral preparations', i.e. a medicinal preparation prepared on prescription by a pharmacist). On the other hand, prescribing physicians must inform their patients that cannabis-based medicines may affect momentary ability to drive and general fitness-to-drive.
The positioning of cannabis as a legitimate medical treatment produces some tensions with other regulatory frameworks. A notable example of this is the so-called 'zero tolerance' drug driving legal frameworks, which criminalise the presence of THC in a driver's bodily fluids irrespective of impairment. On the other hand, it has been observed that there is little evidence to justify the differential treatment of patients taking cannabis-based medicines compared with those taking other medications potentially impairing driving performances.
The aim of this paper is to briefly discuss current Swiss legal issues concerning drivers who are prescribed medicines containing cannabis, as well as to update prescribing physicians on relevant issues and the best guidance to offer their patients.