Investigating predictors of driving immediately after consuming cannabis: A study of medical and recreational cannabis users in Australia

Abstract

This study aimed to explore the length of time cannabis users typically wait between drug consumption and driving a vehicle, and what factors influence such decisions. A total of 839 Australian cannabis users participated in an online survey (26.3% had a prescription for cannabis). Participants ranged in age between 18 years and 75 years (M = 43.3) and 38.2% were female. Driving immediately after consuming cannabis was reported by 41.6% of the sample and waiting 1 h was the next most common response (17%). About one-quarter of participants reported that they waited at least 4 h, thus driving at a time they may no longer be impaired (26.8%). Factors that predicted waiting less time included: a greater frequency of drug consumption (times per day and per month), earlier age of cannabis use onset, using cannabis without a prescription, reporting past-year driving within four hours of consuming cannabis with an illegal drug, and lower perceptions of risk related to driving after consuming cannabis. Participants were asked to report how many days in the next year they would drive within four hours of cannabis consumption, with the most common response being 365 days (37.9% of sample). Given cannabis use is likely to increase through impending decriminalisation and expansion of prescription access, identifying ways to educate cannabis users and extend the length of time they wait between consumption and driving is critical for road safety.