How Long Does Cannabis Last in Your Body?

If you’re taking or considering taking medicinal cannabis, it can be a stressful time for some Kiwis. You may have lots of questions such as; is medical cannabis legal in NZ, how does medicinal cannabis work, and more! One common question that we’re tackling in this blog is how long does cannabis last in your body, and does taking medicinal cannabis impact drug testing in workplaces?

Many medicinal cannabis patients worry that their prescription will show up in drug tests required by their workplace or law enforcement. They also worry that others won’t understand that medical marijuana won’t impair their ability to work or drive. So let’s get to the bottom of these concerns! Keep reading below.

Firstly, what do drug tests check for?

Drug tests in NZ target a few specific substances, one being THC-COOH, a product created when a human liver processes THC. This is looked for in drug testing because it stays in the body for much longer than actual THC and is a reasonably strong indicator that someone has consumed THC.

According to Labtests NZ, drug tests screen for six drugs, including; cannabis (THC-COOH), amphetamine, methamphetamine, cocaine metabolite, opiates and benzodiazepines. Check out Labtests drug testing FAQ.


So, does medicinal cannabis show in a drug test?

Cannabis plants contain CBD, THC (the psychoactive part that makes you feel high in large doses) and a few other compounds. Medicinal cannabis comes in a few forms and different concentrations. Your prescription depends on your health condition, your preferences, and how well your body tolerates your medication.

Medicinal cannabis will show up in a drug test if it contains THC. As many medical cannabis patients’ treatments involve taking their medication regularly, any amount of THC will build up in your body and will most likely show up in drug screens.

Medical cannabis products that may show up in tests are THC isolate products derived purely from THC with a carrier oil and full-spectrum CBD, which contains small traces of THC. Check out our handy guide if you’d like to know more about the differences between different medicinal cannabis products.


How long does cannabis last in your body?

It depends. The time THC is detectable in your system subject to how often and how much you consume. As we’re talking about medicinal cannabis, we will focus on regular consumers of cannabis. People who take medicinal cannabis one or two times a week may get a positive in a urine drug test for up to three weeks, 24-72hrs in a saliva test, or ~30 days in a hair follicle test. For daily users, medicinal cannabis is present in urine for 30+ days, saliva for 24-72hrs, and hair follicles for up to ~90 days.

 Several factors apart from the amount of THC consumed affect how long cannabis stays in your systems, including; gender, genetics, frequency of use, body fat, and metabolism.


Can CBD make you test positive for cannabis?

No! CBD will generally not make you test positive for cannabis in a drug test. This is because drug tests don’t test for CBD, only THC. So, if your doctor prescribed a product without THC, such as a CBD isolate or broad-spectrum CBD, you’ll always test negative.

Full-spectrum CBD does contain traces of THC. Most of the time, you’ll still test negative if drug-screened while taking full-spectrum CBD. However, some products have more THC than others and may have enough THC to show in a drug test.


When could I be required to take a drug test?

There are a few situations where you could be required to take a drug test in NZ. The one we get asked about most is in workplaces. Your employment contract and companies policies will outline the details about when a drug test might be required. The reasons for tests include:

  • Pre-employment screening
  • Random roadside testing
  • Post-incident testing
  • competitive sports testing
  • Reasonable cause testing
  • Rehabilitation
  • Pre-employment/pre-contract
  • Internal transfer

To find out more about workplace drug testing, book a consultation with a Cannabis Clinic doctor. We have experience helping Kiwis navigate these issues and are more than happy to help!

Roadside drug testing by the Ministry of Transport is also becoming increasingly common for their Road to Zero campaign targeting safe driving. Please remember that it is illegal to drive while impaired, so depending on the type of medicinal cannabis product prescribed to you, driving is not advised. 


What does a drug test involve?

A drug test can be performed in three ways; saliva testing, urine testing, or hair follicle testing. Urine testing is the most common, but hair follicle testing is the most accurate.


What happens if I fail a drug test?

If you test positive for a required drug test, Labtests will report the result to the person (or people) indicated in the test’s paperwork. If your test is for work, the impact of the test will depend on your workplace policies. However, required by Police, the consequence will depend on the law and best practices.

If a workplace test comes back positive, your results will not be reported to the Police or any other third party without your permission, according to Labtests NZ. Your result will only be known by you, your hiring manager, HR (if applicable), and the technician who processes your test. All test paperwork is strictly confidential, and you won’t be handed over to Police or put on a database by Labtests.

If you test positive for a qualifying drug (THC) at a roadside drug test, provided you are not impaired, a medical defence will be available if you:

  • Have a current legal prescription for the medicinal cannabis product
  • Have complied with the instructions from the prescriber or manufacturer of the product about driving, consuming alcohol or other prescription medicines while consuming the cannabis product.  

Check out the NZTA website for further information relating to medicinal use and impaired driving


So, how do I prove that my cannabis use is medical or legal?

You can prove your cannabis is for legal, medical reasons by consulting with your GP or Cannabis Clinic specialist doctor. We can help you gather the required evidence that your cannabis use is medical and legal. In addition, we provide letters and documents to your employer for them to have on file and proof that your cannabis use won’t impair your ability to work.

To help you with your peace of mind, we also offer our patients a Medicinal Cannabis Card, which provides you with identification and confirms you’re a Cannabis Clinic patient. This card isn’t a legal document but may help you when you’re driving, flying, or in the workplace.

And of course, our doctors can offer you expert advice and help you navigate conversations and the stigma you may experience as a medicinal cannabis user. We’ll support you every step of your journey to a better life.



We hope this has answered many of your questions about how long cannabis lasts in your body and what drug testing in NZ may entail. If you’re a recreational user and have questions about safer use and more, please check out The Level for unbiased, accurate information. If you’re ready to take the next step in your health journey and see if medicinal cannabis works for you, book a consultation with one of our experienced doctors. We’d love to help you take the first step on your journey.

Book an initial consultation and get started on your next chapter today!

Already a medicinal cannabis patient?

Do you have concerns about drug testing or documentation to prove legal use? Then, book a follow up with your Cannabis Clinic doctor today, and we’ll have your “t’s” crossed and “i’s” dotted in no time.

Book a follow-up with your doctor. We’re always happy to help!

Disclaimer – medicinal cannabis and CBD oil are unapproved medicines in NZ which means that there is no conclusive evidence for their effect, apart from Sativex. Many doctors do not routinely prescribe cannabis medicines. The above article was written for general educational purposes and does not intend to suggest that medicinal cannabis can be used to treat any health condition. Please consult with your healthcare provider. 

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