This Fact Sheet from CARRS-Q provides a synopsis on the facts, tips for staying safe, penalties and future directions.

  • Drug driving is an increasing road safety problem.
  • There is a particularly strong association between drug use and crash involvement, with the risk estimated to be equal that of a driver with a blood alcohol concentration of 0.1 to 0.15%


This fact sheet complements CARRS-Q’s Medication and Driving Fact Sheet.

  • Research demonstrates that an alarming number of motorists are driving after consuming illegal drugs and the occurrence of drug driving in some groups may be greater than drink driving.
  • A ten year evaluation of road crashes in Australia estimated that 1 in 4 drivers killed in road crashes tested positive to drugs other than alcohol.
  • Drug driving is a contributing factor in approximately 10-30% of road fatalities in Australia.

How do drugs affect me?

  • Many drugs can affect our ability to drive safely. These drugs include illegal (illicit) drugs, as well as legal drugs such as alcohol and medicines (prescribed and over-the-counter).
  • Drugs that affect driving include cannabis, amphetamines, benzodiazepines, hallucinogens, antihistamines and opiates.
  • The most commonly used illegal drugs are marijuana followed by speed and ecstacy.
  • Many drugs are highly addictive to the extent that users need them in order to function in their daily routine. Excessive drug use can cause cognitive impairment, which can affect judgement, memory and reaction time.
  • The time it takes to remove drugs from the body can impinge on work and driving performance. An individual can consume drugs in the evening and still have drugs present in his or her body the next day.
  • The level of drugs which will remain in a person’s system over time can depend on a range of factors including the strength of the drug, if it was taken in combination with other drugs, the situation in which it was used and the individual’s metabolism. Driving under the influence of drugs is estimated to be equal that of driving with a blood alcohol concentration of 0.1- 0.15%

Drug use can affect drivers and the driving task by:

  • Slowing down the reaction time – this can be crucial in an emergency situation.
  • Dulling the thinking process making it difficult to multi-task – an essential skill necessary for safe driving.
  • Causing a distorted view of time and distance – reducing your ability to drive safely and identify driving hazards.
  • Stimulating the nervous system, leading to:
    • reduced attention span – not noticing other drivers and/or vehicles;
    • over-confidence in driving skills that is not supported by an actual improvement in driving ability;
    • aggressive and dangerous driving;
    • the sudden onset of fatigue as the stimulant effects wear off; and
    • altering their view and experience of reality, with their actions and responses quite different to what is actually needed. Motorists may be unaware of how much their driving skills are impaired.

Can I have a small quantity of drugs and still drive?

  • Illegally manufactured drugs vary in strength and purity. This makes it difficult to predict the extent to which a person’s driving skills will be impaired. Often drugs are consumed in combination, or with alcohol, and the impairment to driving ability can be much greater. Severe penalties apply to anyone caught driving under the influence of illegal drugs.


The best advice regarding drug use is simply “do not drive” whilst under the influence, however, if you are going to use drugs, plan ahead:

  • Organise a driver who will not be using drugs or alcohol;
  • Make arrangements for alternative transport;
  • Use public transport or ‘grab a cab’; or
  • Speak to your doctor or pharmacist about the potential affect a medication may have on your driving and be aware of the dangers of mixing medications and consuming alcohol.