February 14, 2022

Drugs and driving

woman parking her car

Drug driving is a serious road safety issue.

When you drive under the influence of alcohol or drugs (including some prescription and over-the-counter medications) you pose a danger to yourself, your passengers, and others on the road.

One in four Victorians who use drugs admit to driving under the influence of illicit substances.1

And, within the last five years, approximately 41% of Victorian drivers and motorcyclists who died on the roads and were tested had drugs in their system.1Cannabis and stimulants were the most commonly detected.1

Even in low doses, drugs can significantly reduce your driving skills.2

Read more below about how different drugs can affect driving.

How can drugs impact your driving?

Prescription medication

If you take prescription medication, it’s important to be aware of potential driving risks.

If you're feeling drowsy, aggressive, dizzy, nauseous, light-headed or shaky it can be dangerous to drive as your vision and ability to concentrate might be impaired.2

So, if you’re taking prescribed or over-the-counter medication, always:

  • read labels carefully and follow directions and warnings
  • ask a doctor or pharmacist if the medication is likely to affect your driving
  • arrange alternative transport, if advised
  • be cautious when beginning any new medications as your body may need time to adapt. Adjusting to new sedating medications, such as benzodiazepines or opioids, can take six to eight weeks.3

Want to know more about the impact of medications on driving? Visit the NPS MedicineWise website and search the drug’s potential side effects.


Depressant drugs (like alcohol and benzodiazepines); opioid drugs (like heroin and oxycodone); and Cannabis can all ‘depress’ or ‘slow down’ activity in the body.4

Effects of depressants include:

  • reduced reaction times
  • reduced concentration
  • drowsiness
  • difficulty processing information
  • difficulty doing more than one thing at a time (e.g. keeping your car within its lane while watching for oncoming traffic).4

Combining different depressant or opioid drugs can strengthen these effects and impact your driving skills even more.


Stimulant drugs, including amphetamines and cocaine, ‘speed up’ the body’s activity.4

Effects can include increased heart rate and blood pressure, anxiety and increased sense of ability.4

This can lead to:

  • attention difficulties
  • tendency to fidget
  • aggressive and dangerous driving
  • increased risk taking
  • over-confidence in driving skills.4

So, someone who has recently taken methamphetamine or cocaine is more likely to speed, run red lights and drive erratically.3

Combining different stimulants can strengthen this effect, putting greater stress on the heart and other vital organs. It also increases the risk of psychosis, anxiety and panic attacks.5


Psychedelics, including LSD, magic mushrooms and mescaline, affect mood, perception and cognitive processes.6

MDMA and cannabis may also have some hallucinogenic effects.7

Taking these drugs can lead to seeing or hearing things that aren't really there or experiencing real things in a distorted way.8

The effects of psychedelics vary and can have unpredictable effects on your driving ability.

As a general guide, some of the effects of psychedelic drugs include:

  • hallucinations
  • confused thinking
  • blurred vision
  • reduced coordination.9

The risks of combining drugs

Mixing different types of drugs, whether prescribed or illicit, can impact the brain and body in ways that are dangerous for driving.5

The effects of combining different drugs can be unpredictable,5 but the risk of having a crash while under the influence of two or more drugs is high.10

Combining drugs can increase their effects and reduce coordination, impacting your ability to drive safely.10

This includes mixing illegal and legal drugs, as well as combinations of legal drugs including drinking alcohol while taking over-the-counter or prescription medication. Some examples include mixing alcohol with MDMA, or cocaine with benzodiazepines.

Taking one drug might also make you less aware of the effects of another.

If you’ve been drinking alcohol and using amphetamines, you may not feel the depressant effects of the alcohol, as it's masked by the stimulant effects of the amphetamines.11 This means you may feel capable of driving, but in reality—you might be intoxicated.

Drugs and driving – things to remember

  • In Australia it’s illegal to drive if your blood alcohol level is over 0.05.12
  • It’s also illegal to drive with any quantity of illicit drugs in your system.13 Roadside drug testing occurs in all states and territories.
  • Alcohol and other drugs can affect you long after their immediate impact appears to have worn off.
  • People with drugs in their system pose a higher road risk, even if they feel it’s safe to drive.14
  • You may feel tired or hungover as drugs wear off, this can also impair driving ability.3
  • All drivers, young and old, should avoid driving if they've recently drunk alcohol or taken other drugs.2
  • Speak to a health professional and read packaging information or visit the NPS MedicineWise website before mixing medications with alcohol or other drugs.
  • Tell your doctor about all the drugs that you use (including prescribed, over-the-counter and illegal drugs). They can help you to reduce the risk of unwanted interactions between drugs.

Plan ahead: safe transport

If you're going to consume alcohol or other drugs, including prescription medications, plan ahead to reduce the risk of dangerous driving.

Think about:

  • nominating a designated driver
  • using public transport, taxis or ride share
  • asking a family member or friend to pick you up
  • staying overnight.

Remember, drugs can continue to affect you the next day and, along with tiredness, hangovers and come downs, this can impact your ability to drive safely.3

If you use drugs, the safest option is not to drive.2

More info on safe driving

Have a look at the following pages for more information:

  1. Drug driving - TAC - Transport Accident Commission. 2022 [Cited 31/1/22].
  2. Centre for Accident Research and Road Safety. State of the Road: A Fact Sheet. Brisbane, QLD: CARRS-Q; 2022 [Cited 31/1/22].
  3. Parekh V. Psychoactive drugs and driving. Australian Prescriber. 2019;42(6):182-5.
  4. Brands B, Sproule B, Marshman J. Addiction Research F. Drugs & Drug Abuse: a reference text. 3rd ed. ed. Toronto, Ont.: Addiction Research Foundation; 1998.
  5. Positive Choices. Polydrug use. Canberra, ACT: Australian Government Department of Health; 2014 [Cited 31/1/22].
  6. Nichols D. Psychedelics. Pharmacological Reviews. 2016; 68(2), 264-355.
  7. Parrott A, Gouzoulis-Meyfrank E, Rodgers J, Solowij N. Ecstasy/MDMA and cannabis: The complexities of their interactive neuropsychobiological effects. Journal of Psychopharmacology. 2005;18:572-5.
  8. Leptourgos P, Fortier-Davy M, Carhart-Harris R, Corlett PR, Dupuis D, Halberstadt AL, et al. Hallucinations Under Psychedelics and in the Schizophrenia Spectrum: An Interdisciplinary and Multiscale Comparison. Schizophrenia Bulletin. 2020;46(6):1396-408.
  9. Campbell A. The Australian illicit drug guide: every person's guide to illicit drugs--their use, effects and history, treatment options and legal penalties. Melbourne: Black Inc.; 2001.
  10. Drummer OH, Gerostamoulos D, Di Rago M, Woodford NW, Morris C, Frederiksen T, et al. Odds of culpability associated with use of impairing drugs in injured drivers in Victoria, Australia. Accident Analysis & Prevention. 2020;135:105389.
  11. Schuckit MA. Drug and alcohol abuse: a clinical guide to diagnosis and treatment. New York, NY: Springer; 2006 [Cited 31/1/22].
  12. Drink driving – TAC – Transport Accident Commission. 2022 [Cited 31/1/22].
  13. Drug laws in Australia. Department of Health. 2022 [Cited 31 January 2022].
  14. Monash University Accident Research Centre. Going Solo. Melbourne: Monash University; 2007.

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