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?
Sample Required?
A random urine sample is usually collected for detection of drugs of abuse although they can be detected in blood, sweat, saliva, mother's milk and hair samples.
The Test Sample
What is being tested?
The presence of various classes of abused drugs can be tested for. This usually starts with a 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 groups 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 detected.
How is the sample collected for testing?
A random urine sample is usually collected for the detection of drugs of abuse although they can be detected in blood, sweat, saliva and hair samples can be used on rare occasions. If the test may have the legal implications of the outcome of the test you may be asked to provide a sample from a supervised collection and sign to say that it's your sample.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
The Test
How is it used?
Analysis of urine specimens for drugs of abuse only gives information about current or recent drug use. 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 period of time during which some drugs of abuse can be detected are listed below. There is a lot of variation from one person to another and detection will depend on the dose taken, the frequency and way the drug was taken, the concentration of the urine (influenced by how much fluid has been drunk) and the speed at which the drug is broken down and removed from the body.
| Drug | Lenght 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 much 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 suggests that the concentration of drug present is greater than a specified cut-off concentration for that particular drug. Most UK laboratories use the same concentration to define a positive result and conform to the Substance Abuse and Mental Health Services Administration (SAMHSA) 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
Ask a Laboratory Scientist
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.
