Avoiding impaired driving

Many prescribed medications (some purchased over-the-counter), and all recreational drugs such as alcohol, cannabis, methamphetamine or MDMA can cause impairment. 

Your chances of having an accident are increased when driving under the influence of alcohol, drugs, or prescription medications.

You can be charged even if the substance you took was prescribed by a GP or supplied by a pharmacist. Drivers are required to ensure they are safe to drive at all times.

It’s important you talk with your GP or pharmacist about how the medications they have given you might affect your driving. Tell them honestly about anything else you are taking (e.g. alcohol, cannabis or over-the-counter medications) because sometimes combining medications or combining them with recreational drugs can make the problem much worse.

The types of medications your GP or pharmacist might give you that may impair your driving include:

• strong painkillers
• depression medications
• heart medications
• allergy/hay fever medications
• sleeping pills.

Sometimes medications for psychosis, epilepsy, addiction, nausea and anxiety can also impair your driving.

It can be almost impossible to make a judgement about how impaired you are if you are already impaired.

However, if you are having trouble thinking or speaking clearly, you are probably impaired. If there is any doubt, choose not to drive. 

Other signs of impairment are:

• feeling drowsy
• blurred vision
• headache
• feeling weak
• slowed reactions
• dizziness
• feeling sick.

You can reduce risk by:

• Keeping an eye on how you feel after you first start taking a new medication.
• Talking to your GP or pharmacist about what time of day you should take your medication to avoid times when you are likely to drive.
• Avoiding alcohol if you are taking medication and want to drive.

Stop driving if you feel impaired, call someone to pick you up – or take a bus or taxi.

Don’t stop taking medication because you want to be okay to drive. Your medication is important to your health.

Some people say that taking recreational drugs like cannabis, methamphetamine or MDMA makes them better drivers.

However a significant body of research shows drug use impacts negatively on reaction times.

You may drive more slowly and cautiously, due to cannabis use, but that is not enough to compensate for your slowed reaction time. Combining even small amounts of cannabis with small amounts of alcohol can be especially dangerous because each heightens the other’s effects.

Some facts:

• Recent research showed drivers with cannabis (and no other substances) in their systems were almost twice as likely to be at fault in a fatal car crash than unimpaired drivers.
• Cannabis is the most commonly-detected substance (after alcohol) in drivers who are involved in crashes.
• Studies using driving simulators or controlled road driving tests show cannabis-impaired drivers tend to weave across their lane, drive more slowly, have increased reaction times and crash into things.
• Stimulants can impair your driving because they affect your ability to make good judgments and calculate risk.
• You may experience tiredness, anxiety and irritability as the effects of stimulants wear off, thereby affecting how you drive.
• Stimulants may also stop you from noticing the effects of other drugs you have taken (e.g. alcohol or cannabis).