The law does not seek to penalise drivers who have:
- taken medications in accordance with their current and valid prescription
- accidental or passive exposure to drugs
- low residual levels (below the legal threshold) of a drug in their saliva due to previous (but not recent) use.
You should take your prescription medicines as prescribed by your health practitioner. Remember to check with the practitioner who prescribes you your medicine that it is OK to drive and check the label on the medicine to see if there is a warning.
If you take a dose above what has been prescribed or mix drugs, alcohol or prescription medicines with other medicines, the level of impairment is likely to be increased. Remember to always drive safely – impairing drugs and driving don’t mix.
You have a responsibility to understand the medicines you are taking and if it impacts your driving ability. If you feel affected by your medicine, do not drive. Having a prescription does not allow you to drive while impaired.
Talk to your health practitioner or medication dispenser who can answer any additional questions you may have.
If you receive an infringement notice for a medicine you have a valid and current prescription for, and you have complied with your health practitioner’s instructions, you may apply for medical defence.
ADHD medicines
You will not test positive for prescription ADHD medicines at the roadside using a drug screening test.
The four drugs being tested for at the roadside are THC (cannabis), methamphetamine (meth), MDMA (ecstasy), and cocaine. The screening device does not test for amphetamine; and will not cross-react with any ADHD medicines.
Methylphenidate is not tested for at the roadside or in the laboratory. Amphetamine-based ADHD medications are tested for in the laboratory (but will not test positive at the roadside).
To find out more about specific ADHD medicines and drug testing, please see Roadside Driving Testing - ADHD medication information (PDF, 92KB)
Medicinal cannabis
Even if you are prescribed cannabis, you can still test positive for THC.
Our scientific advisers indicate that people taking cannabis-based medications exactly as prescribed are unlikely to return a positive roadside oral fluid test. However, as with alcohol, drug metabolism varies significantly between individuals based on factors such as dosage, frequency of use, and personal physiology. For this reason, Police cannot advise how long after taking a substance it is safe to drive.
Due to the impairing nature of many drugs, driving safely is most at risk when they have been used recently.
If you are concerned about driving while using medicinal cannabis, you should talk to your health practitioner.
Medical defence
A medical defence is available to drivers who have received an infringement notice for a medicine they have a current and valid prescription for, and they have taken that medicine as prescribed. This includes complying with instructions for driving, and consuming alcohol or other medicines while taking the prescribed medicine.
You can’t apply for medical defence at the roadside. If you present a prescription or medical note to a police officer at the roadside, you are still required to undergo a drug screening test when requested.
Visit the medical defence page to learn more.
I have a prescription, can I just show this to the Police Officer?
No. A prescription cannot stop a driver from undergoing a test or dispute a positive drug screening test result. This is because the officer is unable to validate the prescription at the roadside or know whether you have taken your prescription as prescribed.