How long does cannabis stay in your system?


Hands up if you use cannabis? Don’t be shy or ashamed, we’re not here to judge. We know that it’s the most popular illegal drug in Australia by a long way (just over 10% of Australians use the drug in any given year) so if you use cannabis you’re certainly not alone.

On the other hand, if you use cannabis and then drive or go to work soon after, that’s another story. We will judge you and, if it’s in a workplace, we’ll try to catch you with our workplace drug testing.

So, if you are a responsible person and still want to use cannabis, the questions are, how soon after taking the drug is too soon to drive or go to work and how long does cannabis stay in your system?

We hate to be cryptic, but it depends. Let’s see why:

  • Cannabis, like other drugs and alcohol, affects different people in different ways. It will depend on your size, weight, health and whether you are an occasional or regular user.
  • Another big variable is the amount of cannabis you use and this isn’t easy to quantify. Let’s face it, you don’t buy cannabis from the local chemist so the amount of active chemical (THC) in the drug can vary significantly. The volume of cannabis you ingest will also play a significant part.
  • The effects of cannabis can also last longer if taken with other drugs or alcohol.

Another thing to consider (and this is quite a controversial point) when asking how long does cannabis stay in your system, is whether you’re talking from a safety standpoint or from a standpoint of passing a drug test.

From a safety point of view, the general rule is that most people will be affected by cannabis for somewhere between one to six hours. However, some effects, such as coordination, can be impaired for longer.

From the point of view of passing a drug test, it will depend on the method used. The Cannabis Information and Support website sums this up quite well:

  • Saliva drug testing – generally up to 6 hours but it can be longer. The NSW Government’s guidelines say that THC can be detected for up to 12 hours in a saliva test. Note that this is very similar to the above guidelines for cannabis and safety.
  • Urine drug testing – Between 34 and 87 hours is common, however, for some heavy users it can be nearly 100 days!
  • While not commonly used on roadsides and in workplaces, blood testing can usually detect THC for up to 36 hours.

Perhaps the best advice to take from all this is that trying to work out how long cannabis can stay in your system is like playing roulette. Play it extra safe when taking cannabis and don’t drive or go to work on the same day. It won’t kill you to play it safe, but it might if you don’t!

How long will cannabis stay in your system?

By Michael

Michael is the founder of Integrity Sampling and is responsible for overseeing all national operations. He is based at Integrity Sampling's head office in Melbourne and is also responsible for the co-ordination of drug and alcohol testing within Victoria, assisting in the implementation of drug and alcohol (fit for work) policies and the presentation of drug and alcohol education and awareness programs. You can connect with Michael Wheeldon on LinkedIn

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