People consuming THC could be safe to drive in a matter of hours according to new research which will boost calls for reform to drug-driving laws in Australia.
An analysis of 80 scientific studies by the Lambert Initiative for Cannabinoid Therapeutics identified a ‘window of impairment’ of between three and 10 hours caused by moderate to high doses of THC.
The study found the exact duration of impairment depends on the dose of THC, whether it is inhaled or taken orally, frequency of use and the demands of the task being undertaken while intoxicated.
The researchers found for those using THC in oils, sprays or capsules, the impairment took longer to appear, but lasted significantly longer than for those inhaling.
The team said the findings have implications for drug-driving laws.
Lead author Dr Danielle McCartney from the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney said: “Legal cannabis use, both medical and non-medical, is increasingly common across the world.
“THC is known to acutely impair driving and cognitive performance, but many users are unsure how long this impairment lasts and when they can resume safety-sensitive tasks, such as driving, after cannabis consumption.
“Our analysis indicates that impairment may last up to 10 hours if high doses of THC are consumed orally. A more typical duration of impairment, however, is four hours, when lower doses of THC are consumed via smoking or vaporisation and simpler tasks are undertaken, for example those using cognitive skills such as reaction time, sustained attention and working memory.