New research shows cannabidiol (CBD) is safe for driving and the effects of THC fade in just four hours in a huge boost for drug-driving reform campaigners.

The study, led by the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney and conducted at Maastricht University in the Netherlands, was published today in the Journal of the American Medical Association

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Lead author Dr Thomas Arkell said: “These findings indicate for the first time that CBD, when given without THC, does not affect a subject’s ability to drive. That’s great news for those using or considering treatment using CBD-based products.” 

Lambert Initiative
Professor Iain McGregor from the Lambert Initiative

The Academic Director of the Lambert Initiative Professor Iain McGregor said the results prove the current laws in Australia are not fit for purpose: “With rapidly changing attitudes towards medical and non-medical use of cannabis, driving under the influence of cannabis is emerging as an important and somewhat controversial public health issue. 

“While some previous studies have looked at the effects of cannabis on driving, most have focused on smoked cannabis containing only THC, not CBD, and have not precisely quantified the duration of impairment.” 

Professor McGregor said the study was the first to demonstrate CBD does not impair driving and to provide a clear indication of the duration of THC impairment.

“These results suggest there should be no prohibition around driving after use of CBD products,” he added.

“With respect to THC, laws need to be revised to capture the nuance and subtlety of THC-induced impairment. Prohibition of THC at any concentration in the blood or oral fluid of drivers is problematic since the mere presence of THC does not indicate impairment.