Medicinal Cannabis and Driving in Australia: What Patients Must Know

One of the most important questions patients ask before starting medicinal cannabis is: "Can I still drive?" The honest answer is nuanced — and your doctor must walk you through it before writing your prescription.

The Legal Position in Australia

Australian road laws do not currently provide a medical exemption for medicinal cannabis patients. This means that if you return a positive roadside saliva test for THC — even if you are legally prescribed medicinal cannabis — you may face the same penalties as someone using cannabis illegally.

Roadside drug tests detect the presence of THC, not impairment. THC can remain detectable in saliva for 12–24 hours after use in some individuals, and longer in heavy users or those with slower metabolisms. The detection window does not directly correlate with whether you are actually impaired.

Does CBD Affect Driving?

Pure CBD products (with no THC content) are non-impairing and will not return a positive roadside test for THC. If you are prescribed a CBD-only product, driving is generally not restricted — however you should still confirm this with your prescribing doctor, as some broad-spectrum products may contain trace amounts of THC.

Products Containing THC and Driving

If your prescription contains any amount of THC, your doctor is obligated to counsel you about driving. The general clinical guidance is:

• Do not drive within the period your doctor advises after dosing (commonly 4–8 hours for oils; longer for flower).
• Do not drive if you feel impaired, regardless of time elapsed.
• If you are tested roadside and return a positive result, a valid prescription does not prevent prosecution.
• Some patients on stable, long-term THC regimens may receive different advice from their doctor — this is individualised.

The Road Ahead: Policy Context

There is active advocacy in Australia to reform drug driving laws to account for medicinal cannabis patients. Several parliamentary inquiries have examined the issue. Until the law changes, the practical advice is straightforward: if your prescription contains THC, have a detailed conversation with your doctor about your driving requirements before you start treatment. It may influence the formulation you are prescribed.