Drug test
Technical analysis of biological specimens for drug presence.
A drug test, also known as a toxicology screen or tox screen, is a technical analysis of a biological specimen—such as urine, hair, blood, breath, sweat, or oral fluid/saliva—to determine the presence or absence of specified parent drugs or their metabolites. Major applications include detecting performance-enhancing steroids in sport, screening for prohibited drugs by employers and parole/probation officers, and testing for blood alcohol content (BAC) by police officers.
- types
- Urine, hair, breath, oral fluid, blood, sweat
- common_method
- Urinalysis for workplace and sports; breathalyzer for alcohol
- detection_period_urine
- Hours to days depending on drug and metabolites
- detection_period_hair
- Approximately 3 months for 1.5-inch sample
- detection_period_oral_fluid
- Up to 6–12 hours for THC
- confirmation_method
- Gas chromatography–mass spectrometry (GC-MS) or liquid chromatography–mass spectrometry
Lore & Background
Urine drug testing is one of the most common methods, primarily due to its low cost. It uses an immunoassay based on competitive binding, where a urine specimen migrates by capillary action and drugs compete for antibody binding sites. A common misconception is that a test for a drug class, such as opioids, detects all drugs in that class; however, most opioid tests do not reliably detect oxycodone, oxymorphone, meperidine, or fentanyl. Similarly, most benzodiazepine tests do not reliably detect lorazepam.
Reader's Guide
Drug testing serves critical roles in employment, law enforcement, and sports. Urine analysis is the most widespread method, but it has limitations including relatively high rates of false positives with the enzyme-multiplied immune test. Breath testing for alcohol, typically via a breathalyzer, requires the subject to blow for about 6 seconds and avoid mouth alcohol from recent consumption. Hair testing can detect drug metabolites embedded in hair for up to three months and has been accepted as forensic evidence in several countries. Oral fluid testing mimics blood results for most substances but struggles with THC detection beyond 6–12 hours. The detection window depends on factors such as drug class, amount and frequency of use, metabolic rate, body mass, age, overall health, and urine pH. Confirmatory testing using GC-MS or liquid chromatography–mass spectrometry is standard when initial screens are positive.
Did You Know?
- Heroin and cocaine can only be detected for a few hours after use, but their metabolites can be detected for several days in urine.
- Rapid oral fluid drug tests are not approved for workplace drug testing programs and are not FDA cleared; their use is prohibited in California, Kansas, Maine, Minnesota, New York, and Vermont.
- A breath test for alcohol requires the individual to blow for approximately 6 seconds and contain roughly 1.1 to 1.5 liters of breath.
- Most opioid urine tests do not reliably detect oxycodone, oxymorphone, meperidine, or fentanyl.
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