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How long are drugs in the system?

Information about the amount of time that illicit drugs remain in the person’s system and are able to be detected by random drug tests.

The length of time that drugs can be detected in a person's system is not clear. It depends several factors such as the:

  • type of drug
  • purity of that drug
  • way the drug was used
  • person's general state of health and body metabolism.

Police claim that their purpose of conducting random drug tests is not to detect person’s general drug use. The saliva tests are not designed to detect the residues that may remain in the body from use on previous days. Police say that these will not be detected. The drugs will be detected only at the levels where they are actively impairing a driver’s ability to drive.


Delta-9-tetrahydrocannabinol (THC), the active ingredient in cannabis, can be detected for approximately 3 to 5 hours after use. If it has been swallowed, it may be able to be detected for up to 24 hours.


Ecstasy can be detected for approximately a day after the last use.


Methamphetamine (or speed) may be present for approximately 24 hours.

More information


Australian Drug Foundation (ADF)

The Australian Drug Foundation aims to minimise the harm caused by alcohol and other drugs in Australia. The organisation works in partnership with other organisations to create evidence-based politics and practice that prevent and minimise the harm caused by alcohol and other drugs. Their site has information about the effects of various drugs. There is information about the effects, signs, symptoms, how long after taking the drug before driving, and how to get help with drug use.


Community Offender Advice and Treatment Service (COATS)

The chart below from the Consumer Offender Advice and Treatment Service lists the length of time that the trace of a particular drug can be detected in a person's urine sample.

Note: The urine samples are used by COATS to assess a person's progress in drug rehabilitation schemes and so the levels detected are different to those used by police to detect the presence of a drug for the purposes of drug driving tests.

Community Offender Advice and Treatment Service(COATs)—Urine drug screens (pdf, 565 KB)(opens in a new window)