It can also trace the amounts of illicit substances trapped in the cortex of the hair.

Hair follicle drug testing gives the information of an individual's drug use history. Hair follicle drug testing is a great way to detect the presence of drug in the hair of an individual undergoing the test. It can detect all of the major types of drugs, including marijuana, opiates, methamphetamines, PCP, ecstasy, and cocaine. Once a hair sample of the suspected individual is collected it is preserved in a sachet and sent to a partaking laboratory for drug testing. Hair follicle drug testing is fast and provides more accurate result than any other drug test forms. The process is quite simple and easy and requires a sample of hair in order to accomplish the test. One of the most popular way of drug testing is hair sample drug testing as it has the capacity to detect the presence of drug in the persons body whether or not the same person has used drugs in the past 3 months. Hair drug testing discrete and confidential and so parents can collect a strand of hair from the pillow of their child if they suspect.

All this proves that exposure area is much larger in hair drug testing.