How does THC affect your ability to drive?

There are about 80,000 patients in Australia that are taking medical cannabis for chronic pain, anxiety and various other conditions with the support of their physician and under a completely legal Special Access Scheme managed by the TGA. Yet, somehow the State Governments of Australia make it illegal to drive with any amount of THC in your system. According to studies, THC if you take it regularly can stay in your system for at least 2-3 days (references below).

This means that there is likely

60,000 people every day hitting the roads and driving who would have THC in their system. However, likely 98% of these people are not impaired or affected when driving.  This is the most important thing.

A recent study by McGregor, Arkell at al (2021) talked through multiple points from their study around THC and impairment. Here is the summary



  • Meta-analyses confirm that high levels of immediate THC administration impairs aspects of driving performance.

  • Meta-regression analyses suggest regular cannabis users experience less THC-induced impairment than occasional users.

  • Other factors also influence the degree of impairment observed (e.g. dose, post-treatment time interval, type of skill).

  • Most driving-related skills are predicted to recover within ∼5hrs (and almost all within ∼7-hs) of inhaling 20 mg THC.

  • Oral THC-induced impairment may take longer to subside.

In summary if you are looking to drive after taking your medication

  • Do not drive will impaired
  • Do not inhale cannabis and drive within 6-8hrs, likely add another 2-3 hrs if cannabis is ingested.
  • You are ultimately taking a risk driving

Ultimately, the laws need to change so that existing and future patients can live without fear of losing their license. If you want to make a difference donate or sign the petition to Drive Change (link here). Drive Change is pushing for changes to the law and lobbying Governments.  Or you couldlobby your local state member to change the laws. The Greens Party is pushing this in most states but other parties are not.

Sometimes Governments don’t catch up to change that they created to help people. We just need more studies and likely more technology like we do with alcohol and other drugs.


  1. Mather L.The Issue of Driving While a Relevant Drug, Δ9-tetrahydrocannabinol, Was Present in Saliva: Evidence About the Evidence. Griffith Journal of Law & Human Dignity [Internet]. 2016 [26.10.2021]; 4(2).
  2. Lee D, Huestis MA. Current knowledge on cannabinoids in oral fluid. Drug Testing and Analysis[Internet]. 2014 [26.10.2021]; 6(1-2):[88-111 pp.].
  3. McGregor et al  Determining the magnitude and duration of acute Δ9-tetrahydrocannabinol (Δ9-THC)-induced driving and cognitive impairment: A systematic and meta-analytic review



How does THC affect your ability to drive?


Share Superbly Green

About Superbly Green’s ethos, product range, product benefits and how to order or perscribe products. Can show more content by using this button below.

Share Superbly Green