There are several ways to test for the presence of drugs in the body and the hair follicle drug test is one of them. A drug test tries to determine the presence and amount of certain substances in biological specimens like urine, saliva, blood, sweat and hair. With the increasing usage of drugs, drug testing has become more important, not just for law enforcement agencies but even for sports governing bodies, school authorities and other organizations which require a drug-free environment.

When a substance like marijuana, heroin or cocaine is used, it is metabolized by the body and produces intermediate products called metabolites. Drug testing is the process of trying to detect these metabolites with chemical methods in order to determine whether or not a substance has been used.

Hair gets its nourishment from the blood. When a substance, like a drug, is ingested and metabolized it gets into the blood stream, eventually finding its way into the hair root among other places. As the hair grows out of the scalp the substance remains in the hair. Drugs, whether they are smoked, taken orally or injected into the blood stream find their way to the hair. By subjecting the hair to a chemical analysis, the substances in it are detected.

The hair to be tested may come from any part of the body. The hair strands may come from the head, armpits, chest or even the pubis. The strands will contain the same kind of information about substances that have been ingested. At least 100 – 120 strands of hair, at least half an inch long, are needed for a drug test. Since hair grows at an average rate of half an inch a month, a strand that is half an inch long will show traces of a drug that has been taken over the last 30 days. A longer strand, say an inch and a half long, can show a history of a drug taken in the last 90 days.

The hair follicle drug test has been proven to be quite accurate. It has been shown to be more accurate in detecting low-level drug use compared with the commonly-used urine drug test. The hair follicle drug test can detect substances like cocaine, marijuana, methamphetamine (like Ecstasy), morphine and PCP.

In the hair follicle drug tests, hair strands to be tested are washed prior to application of the test agents. This removes any external substances like residue from shampoos and rinses that might compromise the test results. As a drug testing procedure, the hair follicle drug test not only provides accuracy but also convenience and privacy compared with other standard drug testing methods.