Drug testing in addicts: a comparison between urine, sweat, and hair

The standard in drug testing is the immunoassay screen, followed by a gas chromatography/mass spectrometry confirmation conducted on a urine sample. Recently sweat and hair analyses were proposed for identifying drug abusers. Specimens can be collected under close supervision without embarrassment and are not subject to evasive maneuvers. In contrast with urine, hair analysis has a wide window of detection, ranging from months to years, and provides information concerning the severity and pattern of an individual's drug abuse. Testing individuals for illicit drugs with sweat patches worn continually would provide effective coverage for a week. Studies conducted in a detoxification center have shown that hair analysis is more sensitive for detecting illicit drug use than is urine screening. My experience in drug testing is discussed in the light of the existing literature.