Driving and Medical Cannabis: Practical Info For Patients

Alternaleaf Team
Written by
Alternaleaf Team
Jan 4, 2023
Last updated:
Dec 15, 2023

While it’s common knowledge that it’s illegal to get behind the wheel after drinking too much alcohol, did you know there are also rules about cannabis and driving? Specifically about THC and driving.

Depending on what the medical cannabis prescription contains — THC, CBD, or a combination of both — there are rules for the road. Prescriptions containing THC may impair driving or put you at risk of testing positive, even if you are not feeling impaired.

We’re here to help patients with a medical cannabis prescription in Australia understand the specifics. The following particulars covers cannabis prescriptions — including flower, sprays, and cannabis oil — and driving.

How Does Cannabis Affect Driving?

Cannabis is a very broad term that covers a wide variety of compounds (called cannabinoids) and formulations. Not all types affect driving, but there is one compound in particular that does.

Tetrahydrocannabinol (THC) is a medicinal cannabinoid found in many medical cannabis prescriptions. While safe to use as directed by your doctor, it can lead to intoxicating effects in some doses, hence there are specific laws around it for drivers.

Studies have determined that THC may impact driving performance. For example, drivers may have a slower reaction time.

Yet, not all cannabis use leads to impaired driving. There are some THC-free products available which are not intoxicating — that means an isolate cannabidiol (CBD) product.

Many patients rely on CBD isolate products, which means their ability to drive is not impacted by their medical cannabis prescription.

Can You Legally Drive After Medical Cannabis Consumption?

This all depends on what your prescription contains.

It is illegal to drive under the effects of any intoxicating substance in Australia, including THC, so it’s best not to get behind the wheel after consuming a THC containing cannabis product. The same applies if you have a high tolerance for THC and don’t always feel the intoxicating effects from this cannabinoid.

lights on highway at night
There are no hard and fast rules about how long you'll need to wait after ingestion. Everyone is different.

So how long do you need to wait? It varies for each individual and there’s no straightforward answer. According to the Alcohol and Drug Foundation, THC can be found in your system up to 12 hours later even if you don’t think you’re still experiencing the effects. This timeframe may be dramatically longer if you are a regular or heavy user (days or weeks).

How your body processes and stores THC is very individual. How long it takes your body to process (excrete) will depend on the administration method, duration of use, metabolism, and body composition.

THC is a lipid-soluble molecule, meaning it can build up in your fatty tissues. This may lead to a positive drug test, even if you haven’t used a THC-containing product for a period of time before testing. While you may not be impaired, you may still test positive.

But, when it comes to CBD isolate cannabis oil and driving, there are no lingering effects that impair function. That means CBD isolate cannabis oils, liquids, capsules, and sprays don’t impact your ability to drive safely.

It’s important to understand the difference between a CBD isolate product, and a low-THC or full-spectrum CBD product, the latter still puts you at risk of testing positive despite there being minimal risk of impairment.

Some, including patient advocacy groups like Drive Change, have argued that these driving rules discriminate against patients. There is ongoing debate about how lawmakers should balance patient rights with road safety. For now, cannabis patients who have questions about their prescription and driving should speak with their doctor.

Can You Drive After Taking CBD Oil?

There is an exception when it comes to cannabis oil and driving: CBD isolate products.

If your prescription is an isolate CBD only product, you can legally operate a motor vehicle, according to the Centre for Medical Cannabis Research and Innovation.

This is because there is no scientific evidence that CBD has a negative impact on reaction time, cognitive ability, or task performance. Research indicates that CBD doesn’t change a person’s ability to safely operate a motor vehicle.

For a small percentage of patients, CBD may cause drowsiness or temporarily lower your blood pressure. If you’re not sure, check in with your medical cannabis doctor for clarity on your prescription and to discuss the effects.

Driving and Medical Cannabis Laws By State and Territory

The following information covers the specific laws for each state and territory for driving and THC containing cannabis oil, flower and other products.

There are lots of similarities from region to region, but it's worth knowing what the rules are for your area.

Medical cannabis and driving in Australian Capital Territory

Medicinal cannabis containing THC could trigger a positive road drug test. As per the ACT, “It is currently an offence to drive with THC in a person’s oral fluid or blood. There is no legislative dispensation or defence for the use of medicinal cannabis that leads to a positive road drug test.”

Medical cannabis and driving in New South Wales

New South Wales specifically differentiates between THC and CBD. For patients with a prescription containing THC, it is illegal to drive while under its effects. However, for those with CBD isolate medications (i.e. those containing zero THC), it is lawful to drive if one is not impaired.

Medical cannabis and driving in Northern Territory

In the Northern Territory, “it is illegal to drive while under the influence of drugs.” Drugs of concern include illicit drugs, some prescriptions, over-the-counter medications, and THC. Should an officer suspect any intoxication, they may request a saliva drug test, which tests for THC.

Medical cannabis and driving in Queensland

Queensland has a zero tolerance policy for driving while intoxicated, which may be a result from over-the-counter medications, pharmaceuticals, or medical cannabis with THC.

Medical cannabis and driving in South Australia

The government of South Australia notes that it can take up to five full days for medical cannabis to clear your system. Since a positive test counts as driving under the influence, you can be penalised if pulled over and your test indicates use.

Medical cannabis and driving in Tasmania

While it is an offence in Tasmania to drive while under the effects of any intoxicating substance (THC or otherwise), the state recognises the right of medical cannabis patients to drive with THC in their system. Should THC impair driving, it is then considered illegal.

Medical cannabis and driving in Victoria

Victoria notes that there isn’t enough evidence available about how being a regular cannabis user impacts driving. Those who take THC-rich medical cannabis regularly are advised not to drive in Victoria.

Medical cannabis and driving in Western Australia

Finally, Western Australia advises that “it is an offence to drive with THC present in your system.” They advise patients to speak with their doctor should they have questions about their prescription and driving.

Are Patients Subject to Roadside Drug Tests?

Yes, medical cannabis patients can be pulled over by law enforcement and tested for THC if an officer suspects that you are impaired. You may also be subject to a random road-side drug test despite showing no signs of impairment.

The police may give you a saliva test. The test is then taken to their vehicle and analysed in a matter of minutes.

If you do test positive for THC, more confirmation is needed and additional lab testing may be ordered. This can include urine and/or blood testing.

Penalties for driving under the influence vary based on the substance, the amount, and the state or territory.

The Future of Cannabis Oil and Driving

There are many blanket statements out there about cannabis oil and driving, but cannabis is much more nuanced than that. You should always discuss your individual situation directly with your doctor.

As a patient, what’s important is to understand your prescription and what it contains before getting behind the wheel. Knowing how THC and CBD are different and have different effects is the first step.

Reach out to your doctor if you have questions about cannabis oil and driving. They will be happy to help you better understand your prescription.