A toxicology test checks blood, urine, or saliva for the presence of drugs or chemicals. In rare cases, stomach contents or sweat may also be checked.
Drugs can be accidentally or deliberately swallowed, inhaled, injected, or absorbed through a skin surface or mucous membrane. These include prescription medicines, nonprescription medicine (such as aspirin or acetaminophen), vitamins, nutritional supplements, alcohol, and illegal drugs, such as cocaine and heroin.
A toxicology test may check for one specific drug or for up to 30 different drugs at once. Testing is often done on a urine or saliva sample instead of blood, because urine and saliva tests are usually easier to do than blood tests and many drugs show up in either urine or saliva. Traces of a drug may remain in urine longer than in blood. Urine tests often can detect drug use within the last 5 days. Saliva testing can detect drugs used within the past day.
A toxicology test ("tox screen") can be done to:
Many medicines may change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take. Make a list of any medicines (prescription and nonprescription), herbal supplements, vitamins, and other substances you are taking or have taken in the past 4 days.
You will be asked to sign a consent form that says you understand the risks of the test and agree to have it done. If you are a student involved in competitive extracurricular activities, your parents may also need to sign a consent form before you can be tested.
Talk to your doctor about any concerns you have about the need for the test, its risks, how it will be done, or what the results may mean. To help you understand the importance of this test, fill out the medical test information form (What is a PDF document?).
The health professional taking a sample of your blood will:
When testing for drug abuse, another person will watch you to make sure that the sample you are providing is your urine and that you have not added anything to the sample. The temperature of the urine may also be tested to make sure that it is a fresh sample.
This collection method prevents contamination of the sample. Wash your hands to make sure they are clean before collecting the urine.
The person who collects a sample of your saliva will do it in one of the following ways:
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is no pain while collecting a urine sample. A trained person of the same sex may need to watch you during the urine collection. This may make you feel uncomfortable.
There is no pain while collecting a saliva sample. A trained person will be present to either collect the sample or watch you collect the sample.
There is very little chance of a problem from having a blood sample taken from a vein.
There is no chance for problems while collecting a urine sample.
There is no chance for problems while collecting a saliva sample.
A toxicology test examines blood, urine, or saliva for the presence of drugs. Most toxicology tests determine only the presence of drugs (called qualitative testing) in the body and not the specific level or quantity. Follow-up testing is often required to determine the exact level of a certain drug in the body (called quantitative testing) and to confirm the results of initial testing.
No unexpected drugs are found in the blood, urine, or saliva.
Levels of prescription or nonprescription medicines found in the blood, urine, or saliva are within the effective (therapeutic) range.
Unexpected drugs are found in the blood, urine, or saliva.
Levels of prescription or nonprescription medicines found in the blood, urine, or saliva are too low or too high to be effective (therapeutic) or potentially toxic, if too high.
High levels of prescription or nonprescription medicines may be caused by a drug overdose, either accidental or intentional. A drug overdose may be caused by one large dose of medicine or long-term overuse of a medicine. Interactions between medicines also can cause problems, especially if you start taking a new medicine. A high level may mean that a person is not taking his or her medicine correctly or that the medicine is not being properly processed by the body.
Low levels of prescription or nonprescription medicines may mean that a person is not taking his or her medicine correctly.
Reasons the results may not be helpful include:
Many medicines may change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take.
Other Works Consulted
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
- Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
- U.S. Anti-Doping Agency (2011). Athlete Handbook. Available online: http://www.usantidoping.org/files/active/athletes/athlete-handbook.pdf.
- World Anti-Doping Agency (2004). Guidelines for Urine Sample Collection, Version 4. Available online: http://www.wada-ama.org.
|Primary Medical Reviewer||E. Gregory Thompson, MD - Internal Medicine|
|Specialist Medical Reviewer||R. Steven Tharratt, MD, MPVM, FACP, FCCP - Pulmonology, Critical Care Medicine, Medical Toxicology|
|Last Revised||November 7, 2011|
Last Revised: November 7, 2011
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