Cannabis and driving - get the facts

In Queensland it’s an offence to drive with THC in your system, even if it’s prescribed by a doctor.

Driving whilst under the influence of cannabis is dangerous. Cannabis can affect your judgement, vision,coordination and reflexes – all of which increase your risk of having a crash.

Roadside drug tests detect the presence of THC (delta-9-tetrahydrocannabinol) an active ingredient found in cannabis – including some medicinal cannabis.

The facts

THC is the active ingredient in cannabis and negatively affects many skills required for safe driving such as:

  • attention
  • concentration
  • reaction time
  • judgement

The effects of THC in cannabis depends on a range of factors including:

  • the amount being taken and the concentration of THC
  • how often it’s used
  • your size and weight
  • your overall physical and mental health.

These factors make it difficult to predict how long cannabis will affect driving ability.

Additionally, cannabis usage can affect a person’s awareness. Someone who has taken cannabis may think that they are able to drive safely. However, in reality they may not be able to judge how much their driving has been affected by the use of the drug.


Myth busters

"It is ok for me to drive when taking medicinal cannabis because it’s prescribed medication and not illegal."

No. In Queensland, it is an offence to drive with THC present, regardless of the original source of the drug. Whether sourced illegally or through prescription, drugs that contain THC can affect your ability to drive safely.

"I will know if it’s not safe for me to drive."

Mixing drugs (prescription or otherwise obtained) and driving can be just as dangerous as drink driving. Drugs affect each person differently and some people may not even be aware of the affects a drug is having on them, until it’s too late. Road and traffic conditions can change very quickly when you’re driving. Being able to respond quickly is vital to keeping both yourself and other road users safe.

Someone who has taken cannabis may think that they are able to drive safely. However, in reality they may not be able to judge how much their driving has been affected by the use of the drug.


Tips for keeping safe

Plan ahead

Just like when you consume alcohol, if you have used cannabis, the safest option is to not drive. Use alternatives such as asking someone for a lift, catching public transport or booking an alternative transport service.

Get the right advice

If you’re being prescribed cannabis – or any other drug – for a medical condition, speak with your doctor or pharmacist about how those medications might affect your driving.

Ask if it’s safe to mix any medications or to drink alcohol while you’re taking them. Always follow the recommended dose, read the information and warning messages provided and never take someone else’s medication.

Do you have a medical condition? You might need to report it.

Queenslanders who hold a driver’s licence must inform the Department of Transport and Main Roads if you have a medical condition that may affect your ability to drive safely.

Remember, in Queensland, it is an offence to drive with THC present, regardless of whether the drug is prescribed or otherwise obtained.

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