How long can drugs stay in your system?

If you’ve taken drugs the night before, will drug testing catch you the next day?

During a night out with friends, you’ve taken an illegal drug. You’re not a regular user and it’s only a small amount, so when you get up the next morning you don’t consider the potential consequences of driving to work.

How long can drugs stay in your system? More importantly, how long can drugs be detectable during roadside or workplace drug testing?

Will drug testing catch you out?

The question on how long drugs are detectable is topical, particularly given recent media attention on the subject. This includes quotes from Legalise Cannabis Victoria MP Rachel Payne. She suggested that, “Trace amounts of THC (the psychoactive substance of cannabis) can be detected for up to 30 days after consumption”.

Wow – 30 days! Does this mean you could be caught in roadside testing not only the morning after taking cannabis, but up to a month later?

While it makes for good headlines, the answer is categorially no. That’s because Police in Australia use saliva samples for their roadside drug testing. Using saliva, cannabis – or more correctly THC – recent use may be detected for up to 24 hours.

In workplaces, the situation is a little less clear. That’s because some workplaces use saliva samples for drug testing and some use urine. The up to 24 hours detection period for saliva still applies, but for urine THC can be detected for up to 7 days for casual users and up to 30 days for heavy users.

This is where Ms Payne’s comment comes from. It’s not inaccurate, but it certainly doesn’t tell the whole story.

How long can drugs be detected?

VicRoads – Victoria’s road transport authority – has an excellent table on the windows of detection by drug type and testing method. This provides a snapshot of how long drugs can be detected in your system, using both urine and saliva. For example:

  • For THC in cannabis, the detection period is up to 24 hours for saliva. For urine, it’s up to 7 days for casual users and 30 days for heavy users.
  • For amphetamines and methamphetamines – up to 24 hours for saliva, up to 4 days for urine.
  • Cocaine – up to two days for saliva, up to three days for urine.
  • Heroin – the same as cocaine.

Consider these figures an estimation

You may be wondering why the ‘up to’ qualification is used for all the detection periods. Why can’t the time period be more specific?

The reason is simple. Whenever you use any drugs – alcohol included – how it will affect you and how long it will stay in your system will depend on a range of factors. Some are individual factors – such as sex, age, metabolism and general health. While some are about the drug – such as quantity, purity and whether you’ve taken it with another drug.

This is why you should consider the VicRoads information, and any advice on a drug’s window for detection, as an estimate only.

Saliva drug testing the best method

When it comes to drugs and driving, or drugs in the workplace, the key point is that the police, workplace testers and employers are not concerned whether you take drugs. They’re only concern is that if you do take drugs, you allow ample time for the drug to be removed from your system, so you’ll be able to safely drive or safely work.

This is why Integrity Sampling recommends saliva samples for all workplace drug testing. Saliva drug testing is a more accurate way to determine if people are safe to be at work.


If you’ve taken drugs the night before, will drug testing catch you the next day?

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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