Hair follicle drug testing involves taking a sample of hair from the subject and drug testing it for trace amounts of certain materials, which indicate that drug use has occurred. This form of testing works by detecting and measuring the drug molecules and their specific metabolites that are left behind in the bloodstream after specific drugs have been used. After a drug has been processed by the body, trace amounts of metabolites are left behind. These pass through the bloodstream and are eventually inserted into the hair follicle. A hair follicle drug test covers a period of approximately ninety days.
Hair follicle drug testing works by cutting a hair sample as close to the scalp as possible (about 1.5 inches). This is because the most recent hair is required to get results. Typically, around 50-70 strands of hair (40 milligrams) are required for a standard test; this could vary slightly depending upon the thickness of the hair as well as the pigment color.
If there has been any drug use, it will be clear in the presence of the specific trace chemicals stored in that follicle; the amount of the chemical traces found in the hair can even reveal the extent of drug use during that period. This technique can test for the presence of all 5 drug classes mandated by the Federal Government. These include Marijuana, Cocaine, Phencyclidine (PCP), Methamphetamine (Methamphetamine/Amphetamine & Ecstasy) and Opiates (Codeine, Morphine & 6-Monacteyl Morphine).
Because it offers a higher accuracy rate and is less invasive, hair follicle drug testing is now increasingly being preferred over the traditional urinalysis drug testing.