List no. 04 · Room 3 · Medicines
Prescription medicines and driving
Some ordinary medicines can affect your driving, from some antihistamines and cold and flu preparations to sleeping pills and opioid pain relief. Roadside saliva tests are aimed at a short list of illegal drugs, but the offences of driving while impaired by, or under the influence of, a drug can apply to prescription and over-the-counter medicines too.
General information
This page explains the law in general terms. It is not legal advice, and it cannot tell you what to do in your own matter. For your own medicines, your doctor or pharmacist is the person to ask. healthdirect (1800 022 222) has general information on medicines and driving.
Which medicines can affect driving
healthdirect, the free Australian health information service, lists these among the medicines that may affect driving:
- some medicines for blood pressure, diabetes, nausea, inflammation or fungal infections
- some cold and flu preparations, and some antihistamines
- sleeping pills, and opioids used for pain relief
- epilepsy medicines and diet pills
- medicinal cannabis that contains THC
- some medicines for mental health, including medicines for anxiety, some antidepressants and antipsychotic medicines
The effects it describes include drowsiness, dizziness, blurred or double vision, shakiness, confusion and slower reactions, and it says these can be the same as driving over the legal alcohol limit. Victoria’s TAC makes a similar point: the impairing effect of some medicines can be equivalent to a blood alcohol content of 0.05 or more.
Not everyone is affected the same way. healthdirect says it depends on how your body adapts to the medicine, how long before driving you take it, and what else you are taking; taking more than one medicine, or drinking alcohol with it, raises the chance of being affected.
Read the label, then the leaflet
The TGA requires the makers of medicines to put key information on their labels, including warnings. The example it gives for antihistamines reads:
“May cause drowsiness. If affected do not drive a vehicle or operate machinery. Avoid alcohol.”
Prescription medicines come with a Consumer Medicine Information leaflet, and healthdirect suggests reading it. Some leaflets are specific about timing. The TGA has quoted the leaflet for one sleeping medicine, which warns that it may cause drowsiness the day after taking it and says not to drive until you feel fully awake.
Before driving on a new medicine
A checklist drawn from healthdirect and Transport for NSW.
- Ask your doctor or pharmacist whether it is safe to drive on it, and whether a less impairing medicine is available.
- Read and follow the label and the leaflet.
- Expect the effect to be stronger when you first start; do not drive until you are sure it does not affect you.
- Do not take more than the prescribed dose, and do not stop or change the dose without talking to your doctor.
- Avoid alcohol and other drugs while taking it.
- Do not drive if you have missed a dose you need to control symptoms that could affect your driving.
- If in doubt, arrange other transport.
The offences that can reach medicines
A roadside saliva test will not usually be the issue: Victoria’s TAC says those tests do not detect prescription drugs or common medications such as cold and flu tablets. The offences below are the ones the states’ own pages connect with medicines.
| State | What the official page says |
|---|---|
| NSW | Driving under the influence covers driving while affected by illegal or prescription drugs, found by blood and urine tests. Driving with morphine in blood or urine is an offence unless you can prove it was for medical use. |
| VIC | Driving while impaired by any drug, legal or illicit, is an offence. Victoria Legal Aid also describes a charge of driving with more drugs than prescribed, used where police believe a driver was affected by a drug but no illicit drug shows in the blood test; a not guilty plea would need to show the medicine was taken exactly as the doctor, chemist or dentist directed. |
| QLD | A driver whose ability police reasonably suspect is impaired by any drug may be required to give blood, and can be charged with driving under the influence of liquor or a drug. |
| WA | Drug impaired driving applies to drivers so impaired by prescription or illicit drugs that they cannot properly control a vehicle. |
| SA | Drivers impaired by drugs other than those on the roadside list, prescription or illicit, may be charged with driving under the influence. |
| TAS | Driving under the influence of a drug to the extent of being incapable of proper control of the vehicle is an offence. |
| ACT | It is an offence to drive with certain drugs in your system, illicit or not, and this includes some prescription medications. The driving under the influence offence covers legal and illegal drugs, including methadone, morphine, oxycodone, fentanyl and benzodiazepines. |
| NT | The NT page lists driving under the influence of a prohibited drug among the prior offences that make a later drug driving offence a second offence, and points to the Traffic Act 1987 for full details. |
Your licence and your medical condition
Sometimes it is the condition, not the medicine, that matters. healthdirect says that if you have a medical condition that could affect your driving you need to tell your state or territory licensing authority, which may ask for a doctor’s report, and that driving with such a condition can be a criminal offence and may affect your insurance. It also notes that some medicines make driving safer by controlling a condition such as diabetes, epilepsy or heart disease.
Medicinal cannabis has its own rules in each state; they are on the medicinal cannabis sheet.