Drugs of abuse
At a Glance
Why Get Tested?
To detect or exclude the presence of abused and/or illegal drugs. This may be carried out for a number of reasons including a pre-employment screen or to comply with a drug rehabilitation programme.
When to Get Tested?
- If you apply for a job where drug screens are carried out as a routine. Personnel with drug and alcohol problems have worse records for accidents and absenteeism; for this reason many employers screen all job applicants prior to appointment
- If you have admitted having a drug problem and have enrolled in a detoxification or drug rehabilitation scheme
- If you believe you may have taken a drug accidentally or been given a drug without consent (e.g. drink spiking)
- If you are admitted to hospital in an emergency and doctors think that your treatment could be improved if drug abuse could be proved or excluded
- If you take part in a sport at a professional level
- For legal reasons (e.g. child custody cases).
Sample Required?
A random urine sample is usually collected for detection of drugs of abuse although they can be detected in blood, sweat, saliva and hair samples.
The Test Sample
What is being tested?
The presence of various classes of abused drugs can be tested for. This usually consists of an initial screen where the drug group (e.g. opiates) is detected; positive results are then followed up by a more specific test which identifies the individual drug taken (e.g. morphine).
A drugs of abuse 'screen' usually covers the most commonly abused drug classes which are the opiates, benzodiazepines, barbiturates, cannabinoids, amphetamines (including ecstasy) and cocaine. Drugs used in the treatment of opiate addiction (methadone and buprenorphine) are also often searched for.
How is the sample collected for testing?
A random urine sample is usually collected for detection of drugs of abuse although they can be detected in blood, sweat, saliva and hair samples. If there are any legal implications of the outcome of the test you may be asked to provide a supervised collection.
The Test
How is it used?
Analysis of urine specimens for drugs of abuse only gives information about current or recent drug usage. A urine specimen taken more than 2-3 days after a period of 'drug abuse' is likely to be negative on screening for most substances. Cannabis is the notable exception to this, and can remain at detectable concentrations in urine for 2 weeks.
The approximate detection times for some drugs of abuse are listed below. There is a lot of variation from one individual to another and detection will depend on the dose administered, the frequency and route of administration, the concentration of the urine and the speed at which the drug is broken down and removed from the body.
| Drug | Length of time it can be detected in urine |
| Alcohol | up to 1 day |
| Amphetamines & Ecstasy | 1-3 days |
| Barbiturates | 1-3 days |
| Benzodiazepines | 1-3 days |
| Cannabis (THC) | up to 2 weeks |
| Cocaine | 1-3 days |
| Codeine | 1-2 days |
| Dihydrocodeine | 1-2 days |
| Heroin (morphine) | up to 1 day |
| Methadone | 1-3 days |
Drugs of abuse can also be detected in other body fluids such as saliva but with saliva the period of detection is considerably shorter than in urine.
When is it requested?
To detect or exclude the presence of abused and/or illegal drugs. This may be carried out for a number of reasons including a pre-employment screen or to comply with a drug rehabilitation programme.
What does the test result mean?
A result reported as 'positive' in a screening test implies that the concentration of drug present is greater than a specified cut-off concentration for that particular drug. Australian laboratories use the same concentration to define a positive result and conform to the Australian Standard AS4308 guidelines.
The sensitivity of drug detection will be reduced in dilute urine specimens. At concentrations below the cut-off limit, the drug will normally be reported as not detected.
Is there anything else I should know?
Certain foods and prescribed drugs can interfere and give false positive results with the initial screen for certain drug groups (e.g. taking codeine or eating poppy seed bread can give a positive opiate result) and for this reason positive results are usually confirmed by a second, more accurate laboratory method before they are reported.
Common Questions
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Article Sources
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
