Just like drinking and driving, there are road rules for medicinal cannabis use that patients in Australia must follow. Even if you don’t feel impaired, medicinal cannabis may slow your responses or put you at risk of testing positive on a drug test so it’s important to understand your prescription before getting behind the wheel.

Cannabis has more than 100 compounds, or cannabinoids. The two most often extracted for medicinal cannabis are cannabidiol (CBD) and tetrahydrocannabinol (THC). 

What is THC? 

THC is commonly understood to be the compound in cannabis that can get you high (causing euphoria or relaxation). THC can be found in a range of medicinal cannabis products. While it is safe to use THC as directed by your doctor, it may affect your judgement, vision, coordination and reflexes, so it can impact your ability to drive. 

What is CBD? 

CBD on the other hand is a non-intoxicating compound. Many patients rely on CBD isolate (CBD only) products that contain no THC. According to the Centre for Medical Cannabis Research and Innovation, if your prescription is a CBD isolate product, you may legally operate a motor vehicle if you’re not impaired. It’s important to discuss your prescription with your doctor and understand if you’re being prescribed a CBD isolate product, a low THC medication, or a full spectrum CBD product (may contain other compounds including THC). You may test positive in a drug test with a full spectrum CBD product even though you may not feel impaired. CBD medications may cause drowsiness for some patients so check with your doctor about the effects of your prescription. 

Can you legally drive after taking medicinal cannabis? 

It’s illegal to drive under the influence of any intoxicating substance in Australia, so it’s best not to get behind the wheel when using a medicinal cannabis product that contains THC. 

In all Australian states and territories except Tasmania, there’s no medical defence for using prescribed medicinal cannabis products that contain THC while driving, even if you don’t feel impaired. Medicinal cannabis patients can be pulled over by law enforcement and tested for THC if an officer suspects you are impaired or as part of random roadside drug testing. Penalties for driving under the influence vary based on the substance, amount, and the state or territory. 

According to the Alcohol and Drug Foundation, THC can show up in a saliva test for 12 hours for infrequent users, and up to 30 hours for frequent use. It can be even longer if you’re a regular user as THC can build up in fatty tissue. In urine, THC can show up for 10–30 days or longer. How long THC’s effects last and how long it stays in your system depends on your body and metabolism, administration method and duration of use. 

While it’s an offence to drive under the effects of any intoxicating substance in Tasmania, the state recognises the right of medicinal cannabis patients to drive with THC in their system if they are not impaired. The challenge is that there is no reliable standard test for impairment, so it is a subjective assessment by the officer who may pull you over. 

Patients taking CBD isolate (THC free) medications can lawfully drive in any Australian state or territory if they are not impaired. Check with your doctor to better understand your prescription and how it may impact driving as many medicinal cannabis products do not contain THC.

Interested in exploring plant-based therapies? Connect with a doctor to learn how plant-powered medicines could help you feel your best. 

Further Reading