During hair follicle testing, the specimen collector collects 90 to 120 strands of the donor's hair for a sample, secures the hair sample in foil, and documents its collection, according to LabCorp. The specimen collector cuts the hair at the scalp and ships it to a testing laboratory. The hair follicle test detects illicit drugs in the donor’s system. Although different labs may practice different collection methods, the testing procedure is the same, notes Drugs.com.
At the lab, technicians test the strands using a special test performed with enzyme-linked immunosorbent assay and gas or liquid chromatography/tandem mass spectrometry, notes LabCorp. The test looks for drugs and their metabolites incorporated from the bloodstream into the hair’s matrix during drug use. Samples that are negative for drugs are generally available to the test requester within 72 hours of specimen receipt by the lab, while those samples that are positive for drugs may require additional processing time of an additional 72 hours.
Hair follicle testing detects a range of different illegal or illicit drugs, reports LabCorp. The test may screen for amphetamines and methamphetamines, marijuana, cocaine, phencyclidine, and opiates or any of their metabolites.
Although hair growth rates differ, a 1.5-inch sample of hair generally offers a 90-day window into the donor’s use of drugs, suggests LabCorp. Drugs are detectable within the hair within seven to 10 days from the time of use, which is the amount of time it takes for the affected follicle to emerge from the scalp.