As of 2022, there have been more than 248,000 scripts approved1 for medicinal cannabis (also referred to as ‘medical marijuana’ – learn about the history and implications of this term here) since it was legalised Australia-wide in 2016.
If you’re one of the thousands of patients living with a chronic condition in Australia who have received a medicinal cannabis prescription, it’s important you’re aware of the rules, risks and restrictions that exist if you are going to drive. Especially if you have been prescribed a cannabis treatment containing THC.
In this article, we’ll answer your questions about driving as a medical cannabis patient in Australia.
Should you drive while taking medicinal cannabis?
Because no two patients are the same, the question of whether or not you should drive while taking medicinal cannabis treatments will also vary from patient to patient, depending on the effects you experience while taking your treatments. Currently in Australia, it is legal for you to drive as a medical cannabis patient as long as you have no amount of the cannabinoid THC in your system. But there are a few other things to consider when deciding whether or not to drive while taking your treatments.
Any time you take your prescribed (non-THC) cannabis treatments or any other medication or legal substance that has an effect on the mind and body, you should wait until you are confident that you are safe to drive and you are not experiencing any impairment or adverse side effects before you do so. You should not drive while impaired by CBD or any substance – even if it is legal for you to have it in your system. So if you are experiencing any symptoms like dizziness, low blood pressure or drowsiness while taking your treatments, you should always consider whether it is safe for you to drive and wait until the effects have worn off and you are feeling better before you get behind the wheel.
The most important restriction to note is that it is currently illegal to drive with any amount of THC in your system in Australia (except Tasmania), even with a valid prescription. This means that if you are prescribed a medicinal cannabis product containing THC, you will need to wait until the medication has left your system before you drive. This is challenging given that the amount of time cannabis stays in your system can vary from patient to patient and is dependent on factors like the type of cannabis consumed, the amount of THC in the cannabis, the method used to consume it and the frequency of consumption. But under the current laws in Australia, if you take a medication containing THC and test positive for THC in a mouth swab test, you can lose your licence.
Is it legal to drive while taking CBD?
CBD-containing cannabis treatments that do not contain any THC are legal to have in your system while you drive. You should always know which cannabinoids are in the cannabis treatments you are prescribed and understand the driving restrictions that exist for those treatments as well as the effects you experience when you take them. Some CBD treatments – like CBD oils – do contain THC, while others don’t. Check your treatment label and talk to your doctor before you drive while taking any cannabis treatment.
Even if your prescribed treatment doesn’t contain any THC, you should always pay attention to the effects you experience while taking it and ensure you aren’t driving while impaired. While CBD tends to have a minimal side effect profile, it can cause side effects like drowsiness and fatigue in some patients. Always make sure you feel safe, alert and confident before you get behind the wheel and wait for side effects to wear off before driving.
Is it legal to drive while taking THC?
No. It is not legal to drive with any amount of THC in your system in all states in Australia, even if you are a medicinal cannabis patient with a valid prescription. If you choose to take THC or do not wait long enough for the THC to leave your system before you drive and you test positive for THC in a mouth swab test, you can lose your licence.
These laws exist because THC is a psychoactive cannabinoid which can affect cognitive and motor skills that are needed for safe driving, including attention, judgement, vision, coordination and memory. However, because THC can be detected in the body for up to weeks after the initial cannabis consumption, these laws can unfortunately unfairly discriminate against legal medicinal cannabis patients who may face fines and loss of their licence even when they are unaffected and unimpaired by their medication at the time of testing. In fact, cannabis is the only legally prescribed medication for which you lose your licence when testing positive for presence, not impairment (except in Tasmania). Tasmania is the only state in Australia that allows unimpaired drivers who have been legally prescribed medicinal cannabis to lawfully drive.
How does cannabis affect driving?
Any substance that has an effect on the mind and body is capable of affecting your ability to drive. This is true of both legally prescribed and recreational substances, as well as both plant-based and standard treatments. So any time you start a new medication or substance, change your dose or make any changes to your treatment plan, you should always wait and ensure you are not experiencing any effects or side effects which may impact your ability to drive before getting behind the wheel.
When it comes to measuring cannabis impairment, science tells us that there are several factors which play a role – including dose, mode of ingestion, length of treatment and individual factors like weight and metabolism. In 2020, a landmark study led by the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney and conducted at Maastricht University in the Netherlands found that CBD does not impair driving, while moderate amounts of THC produce mild driving impairment lasting up to four hours.2 A 2022 study led by the same group found that 1500mg, the highest daily medicinal dose of cannabidiol (CBD), has ‘no impact on people’s driving or cognitive abilities.’3
The results from these studies reassure us that patients using CBD-only products are most likely safe to drive, and help us understand the duration of impairment for patients using THC-dominant products. But since driving laws in Australia use a zero-tolerance policy for THC in drivers, the law still dictates that patients consuming THC should not be driving.
Another 2022 study4 conducted by researchers at the University of Sydney’s Lambert Initiative which analysed all available studies on the relationship between driving performance and concentrations of THC in blood and saliva found ‘blood and oral fluid THC concentrations to be relatively poor or inconsistent indicators of cannabis-induced impairment.’ This is in contrast to the much stronger relationship that can be seen between blood and alcohol concentrations and driving impairment.
‘Higher blood THC concentrations were only weakly associated with increased impairment in occasional cannabis users while no significant relationship was detected in regular cannabis users.’
– Lead author Dr Danielle McCartney, Lambert Initiative for Cannabinoid Therapeutics
So while this research does not suggest there is no relationship between THC intoxication and driving impairment, it does call into question the validity of the methods used to assess cannabis-related impairment in drivers in Australia. This highlights the need for more reliable methods of assessing cannabis-impairment in drivers and a reform of the cannabis-driving laws which unfairly impact patients who are using legal medicinal cannabis products who cannot currently drive, even when they are not impaired.
The findings of this study were reported on The Project, Network 10:
How long after consuming cannabis is it safe to drive?
If you take a medicinal cannabis product which contains none of the cannabinoid THC, such as a CBD-only oil, then it is safe for you to drive provided you are not experiencing any adverse side effects like dizziness or low blood pressure. You only need to wait until you are certain you are not experiencing any side effects which impact driving before you get behind the wheel. CBD-only products will not show up on a drug test and it is legal for you to drive after taking these.
If you take a medicinal cannabis product containing THC, the answer to this question is a little more complicated. Because it is illegal to drive with any amount of THC in your system, and because the amount of time it takes for THC to leave your system varies so much from person to person, there is no definitive answer to how soon you can drive after consuming THC. Although the above research tells us that the impairing effects of THC fade after four hours of having consumed it, Australian police test for THC presence – not impairment – when drug testing drivers. So it’s important to understand how long cannabis can stay in your system before you drive as a cannabis patient who consumes THC.
How long does cannabis stay in your system?
Unfortunately there is no definitive answer to this question, as it varies from individual to individual depending on a range of factors, such as:
- The amount of THC / cannabis you consume;
- How often you consume cannabis;
- Your body fat percentage;
- Your metabolism;
- How much exercise you do, and
- The type and sensitivity of the drug test you take
Generally, random roadside saliva tests can detect THC for about 12 hours5 after use in people who use cannabis less frequently. But for those who frequently use cannabis, such as medicinal cannabis patients who use cannabis to help treat chronic conditions, THC can usually be detected for around 30 hours5 after use. Again, these numbers will vary from person to person.
For other types of drug tests, which may be required in certain workplaces or other settings, cannabis can be detected in your system for even longer, including up to 6 days for blood tests,6 up to a month for urine tests5 and up to 3 months for hair tests.7
Because it is so difficult to know when and if you might legally be able to drive after consuming THC, if you are a medicinal cannabis patient who has to drive frequently for work or other activities, you may want to consider a CBD treatment rather than a THC one under the current driving laws in Australia. Ensure you are open and honest with your prescribing doctor about your driving status and current situation so they can provide you with a treatment plan that works best for you.
Driving and cannabis law reform in Australia through Drive Change
Drive Change is an Australian law reform campaign fighting to give medicinal cannabis patients the same rights as other patients. They are a team of educators and advocates who believe that current drug driving laws ‘fail to improve road safety, discriminate against medical cannabis patients and impede public health outcomes.’
Drive Change proposes equal rights for legal medical cannabis patients through the following solution:
‘The government implements Australia-wide uniform drug driving laws to allow for a complete defence to the presence of THC in a driver’s oral fluid or blood when:
- The driver has a valid doctor’s prescription for a medicine containing THC;
- The offence does not involve dangerous or reckless driving; and
- An officer cannot establish driver impairment.’
Visit Drive Change to learn more about how you can support the campaign and help create equal driving rights for legal medical cannabis patients.
Where can I learn more about the cannabis driving laws in my state?
Click on these resources to learn more about the local driving laws in your state:
New South Wales
The bottom line
Knowing whether or not you should drive as a medicinal cannabis patient can be difficult. But no matter what your situation is, you should never drive while impaired. Patients who take THC-free / CBD-only medicinal cannabis products can safely and legally drive provided you are not experiencing any adverse side effects that might impede driving ability. But patients taking THC medicinal cannabis products can face fines and even the loss of your licence if any amount of THC is detected in your system in a roadside test.
It’s important that you’re aware of the cannabinoids / ingredients in your prescribed cannabis treatment and any driving restrictions that exist for your treatment in Australia. You should always be honest and open about your driving status, situation and needs as a patient so your doctor can provide you with the best care possible and tailor a treatment plan that works for you.
Help create equal driving rights for legal medical cannabis patients by visiting Drive Change.
- MacPhail Sara L., Bedoya-Pérez Miguel A., Cohen Rhys, Kotsirilos Vicki, McGregor Iain S., Cairns Elizabeth A. Medicinal Cannabis Prescribing in Australia: An Analysis of Trends Over the First Five Years. Frontiers in Pharmacology Volume 13, 2022. DOI=10.3389/fphar.2022.885655, ISSN=1663-9812
- "Cannabidiol In Cannabis Does Not Impair Driving, Landmark Study Shows". The University Of Sydney, 2022, https://www.sydney.edu.au/news-opinion/news/2020/12/02/Cannabidiol-CBD-in-cannabis-does-not-impair-driving-landmark-study-shows.html. Accessed 16 Aug 2022.
- McCartney D, Suraev AS, Doohan PT, et al. Effects of cannabidiol on simulated driving and cognitive performance: A dose-ranging randomised controlled trial. Journal of Psychopharmacology. May 2022. doi:10.1177/02698811221095356
- McCartney D, Arkell T, Irwin C, Kevin R, McGregor I. Are blood and oral fluid Δ9-tetrahydrocannabinol (THC) and metabolite concentrations related to impairment? A meta-regression analysis. Neuroscience & Biobehavioral Reviews, Volume 134, 2022, 104433, ISSN 0149-7634, https://doi.org/10.1016/j.neubiorev.2021.11.004.
- "Roadside Drug Testing - Alcohol And Drug Foundation". Adf.Org.Au, 2022, https://adf.org.au/insights/roadside-drug-testing. Accessed 16 Aug 2022.
- Karschner EL, Schwilke EW, Lowe RH, Darwin WD, Pope HG, Herning R, Cadet JL, Huestis MA. Do Delta9-tetrahydrocannabinol concentrations indicate recent use in chronic cannabis users? Addiction. 2009 Dec;104(12):2041-8. doi: 10.1111/j.1360-0443.2009.02705.x. Epub 2009 Oct 5. PMID: 19804462; PMCID: PMC2784185.
- Himanshu Khajuria, Biswa P. Nayak, Detection of Δ9-tetrahydrocannabinol (THC) in hair using GC–MS, Egyptian Journal of Forensic Sciences, Volume 4, Issue 1, 2014, Pages 17-20, ISSN 2090-536X, https://doi.org/10.1016/j.ejfs.2013.10.001.
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