Drug Detection Times

How long will a positive drug test result continue?

Unfortunately there is no simple answer for how long a positive drug test result will continue. 

The exact time frame required to return a negative test will depend upon a large variety of factors. These factors include the health of the person, the type of test conducted and the strength, amount 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 for 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 horrendously 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 short "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 also have no idea exactly how strong the drug was to start with and we have no idea about the total amount of the drug that might have been taken (illicit drugs don't tend to be provided with fabulous labels displaying volume and  % strength or be separated into individually packaged "doses").

We've provided a comprehensive explanation of the issues below including the following information:

• What is a detection period?
• So can we just use the detection period tables?
• Cut-off levels - what are they?
• Understanding cut-off levels and impairment
• Drug testing levels are different in each Country
• Drug testing cut-off levels can be different in each Organisation
• What are the major 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 simply the amount of time after consuming a drug that a particular testing method can still show a positive result.

For some methods (blood or saliva) this is usually measured in hours or days and in other cases in days or weeks (urine or hair).

So can we just use the detection period tables?

Detection periods can vary dramatically between people due to many factors (such as speed of metabolism, gender, drug interactions, genetic traits, age of the person or the type and strength of drug and the amount 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. This page contains some useful information 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 any level of the drug. Interestingly, not many people are aware of this!

A “cut-off” is the concentration at or above which a laboratory will deem to be a "positive" result. Cut-offs are usually set arbitrarily by an independent committee/ government body and reflect what most laboratories can reliably duplicate, generally reflect some recency of use and attempt to avoid extraneous influences such as passive inhalation or naturally occurring amines etc.

Drug testing Cut-off levels are different in each Country

In Australia and in the United States, 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 in each Organisation

Some organisations also adopt different cut-off levels for various drug classes. This means that anybody purchasing a home drug test kit should check the relevant cut-off level that might apply before selecting a 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.

What are the major 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.

Having noted these limitations, some detection tables are provided below. 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.

These tables assume that the Australian Standard cut-off levels are used for the applicable substances listed.

Detection Tables (Urine & Saliva)

Stimulants