Key findings:

• Prescribed cannabis use among the EDRS and IDRS samples were uncommon (15% and 7%, respectively)
• Among those who used prescribed cannabis, most contained THC (EDRS: 96%, IDRS: 97%)
• Among those who used prescribed THC containing products and reported recently driving), most reported driving within three hours of consuming prescribed cannabis in the past 6 months (EDRS: 84%, IDRS: 76%)

Discussion: Although prescribed cannabis use was relatively uncommon in these two samples of people who regularly use drugs, most participants who had used THC containing products reported driving within three hours of consumption. Few participants (n<5) reported being detected by roadside drug testing after such use but nevertheless remain at risk of positive roadside drug tests and criminal sanctions. However, these findings are not representative of all people who are prescribed cannabis. In a study of 806 Australian medical cannabis patients, 35% of drivers reported ‘typically' driving within three hours of consuming cannabis in the past month. Taken together, these results add to calls for a review of the regulatory framework governing prescribed medicinal cannabis and driving in Australia, particularly given the differential treatment of medicinal‑cannabis patients compared with those taking other psychoactive medicines.