How long will a drug continue to return a positive result? (Detection Periods)
Unfortunately there is no simple answer to this question. As a result many myths have emerged claiming that certain drugs such as marijuana will give a positive result from a single use, weeks, months or even years after consuming it.
The exact time to return a negative test will depend upon a variety of different factors such as the health of the person, the type of test conducted and the strength and history of previous consumption of the drug. This section should help you to understand detection periods and provide a general guide regarding the detection periods of various drugs.
Detection Periods - Summary
Ever heard that casual use of "Marijuana will show a positive result for 3 months in a urine test"?, or even "six weeks" or even "4 weeks". Normally explanations of erroneously long detection periods such as these are mixed with some scientific facts (such as THC being highly fat soluble). Yes, marijuana is highly fat soluble, however it also has quite a fast "half life" so that casual use of the drug is likely to only present a positive result for 1 to 2 days in a urine test (however this could be 30 days from regular or chronic use).
The time frame CAN VARY from person to person simply because all people have different conditions of general health, different fluid intake, metabolism etc, we have no idea exactly how strong the marijuana was to start with and we have no idea about the total amount of the drug that might have been taken (unless this has been scientifically established).
We have provided a comprehensive explanation of the issues below including the following information:
- What is a detection period?
- So can I just use the detection period table?
- Cut-off levels - what are they?
- What are the limitations?
- Detection Tables
However if you are in doubt and facing a drug test, or if you want to responsibly self-manage consumption so that you won't show a positive result in a drug test with the added benefit that you also have much less chance of exposing yourself and others to risk; you can also test yourself in the privacy of your own home.
What is a detection period?
A detection period is the amount of time after consuming a drug that a particular testing method can still show a positive result.
As you can see in the chart opposite, for some methods this is measured in hours and in other cases in days or weeks.
Note that the detection period applied for hair testing in this chart is 30 days, (rather than the often cited up to 90 day range) in order that the relative differences between all of the methods can be easily seen. However hair testing is very rare in comparison to urine testing, particularly in Australia.
"So can I just use the detection period table?"
Detection periods can vary dramatically between people due to many factors (such as disease state, gender, drug interactions, genetic inheritance , age of the person or the type of drug and way in which it is taken), so any reference to detection periods needs to be taken as a very rough guide only.
Detection period tables should not be relied upon to determine detoxification time or to determine when a person will provide a negative result to a drug test. We have provided some additional information under detection periods which should be helpful for people wanting to understand this issue more thoroughly.
Cut-off levels - what are they?
Drug testing normally involves establishing the concentration of a drug above a certain level rather than just finding the presence of the drug. Interestingly, not many people are aware of this! A “cut-off” is the concentration of a drug at or above which is deemed positive by a laboratory analysis for that drug. Cut-offs are set for laboratory standardisation purposes, the detection period and to exclude defences based upon passive inhalation.
Drug testing Cut-off levels are different in each Country
In Australia and in the United Sates, expert committees have formulated and published recommended cut-off levels for a number of drug classes in what are referred to as "Standards". These cut-off levels are not exactly the same between countries, for example the opiate cut-off level for urine testing in the United States is 2000ng/ml whereas the cut-off level in Australia for the same drug is 300ng/ml. This is a fairly dramatic difference (US is 666% higher than Australia).
Drug testing Cut-off levels can be different between Organisations
Some organisations also adopt different cut-off levels for various drug classes. This means that anybody purchasing a home test kit should check the relevant cut-off level that might apply before selecting a particular test.
Naturally it can be a waste of time and money relying upon a test kit if it uses a different cut-off level to what is actually applied in a policy.
OK - so what are the limitations?
People often fall into the trap of just looking at a detection period table and expecting that the time period stated in the table will apply to them.
The problem with this is that although detection period tables can be helpful in providing a general guide, they also have major limitations. The following table presents some of these limitations.
|Everybody is different||People have different metabolic rates, ages and general health status (for example fitness and disease). All people tend to break down drugs at different speeds.||Even if 2 people consume the same amount of a drug, they will most likely have different concentrations of the drug in their system over time|
|Different route of Administration||If a drug is smoked as opposed to injecting it, this could lead to markedly different detection periods||For example taking opiates orally will lead to substantially different concentrations in the blood and subsequently alter the detection periode|
|Drug consumption is different||Some people might consume a large amount of a drug, while others consume less. Also some people might frequently consume a drug and others only occasionally.||Frequent use of a drug can increase the amount of drug/metabolite in the body and take longer to remove|
|Cut-off levels are not always consisten||Some Countries and Organisations use different Standard Cut-off levels. For example the cut-off level for Opiates in the US is 2000ng/ml compared to 300ng/ml in Australia||If a lower cutoff level is used, the drug detection period will be extended and visa versa.|
Having noted this general warning, a detection table is presented in the following table. As with all information provided on this site, this information is subject to our disclaimer policy which can be viewed in full by following the link at the bottom of this page. This table assumes that the Australian Standard cut-off levels are used for the applicable substances listed.
Detection Tables (Urine)
Dexamphetamine Black Beauties, Crosses, Hearts
Attention deficit hyperactivity disorder (ADHD), obesity, narcolepsy
Cocaine (Injected, smoked, sniffed)
Coke, Crack, Flake, Rocks, Snow
Local anaesthetic, vasoconstrictor not available for medical use in Australia
Hallucinogens and Other Compounds
Magic Mushroom, Purple Passion, Shrooms
Amphetamine and Phenethylamine variants (Oral)
DOB, DOM, MDA, MDMA, MDEA, 2C-T2, 2C-B, PMA, MBDB, 4MTA Adam, Ecstasy, Eden, Eve, Nexus, STP, XTC
Opioids and Morphine Derivatives
Codeine (Injected, oral)
Aspalgin, Codiphen, Codis, Codral, Dymadon, Panamax, Mersyndol, Panadeine, Panalgesic, Panamax
Heroin (Injected, smoked, sniffed)
Diacetylmorphine, Horse, Smack
Methadone (Injected, oral)
Physeptone, Methadone Syrup
Analgesic, treatment for opiate dependence
Beer, Wine, Spirits
Antidote for methanol poisoning
Barbiturates (Injected, Oral)
Anaesthetic, anticonvulsant, hypnotic, sedative, Phenobarbitone (anticonvulsant) is the only Barbiturate available for human medical purposes in Australia (also used by vets)