Hair Drug Test

Though the purpose of any drug test is to determine if an individual has used a particular drug, or any drug, within a certain time frame, there are three main ways to administer a drug test. Drugs can be detected through a blood, urine, or hair drug test. In all three cases, the reference sample has to be collected.

When a hair drug test is administered, an individual hair can be tested for current drug use and even history of drug use. A hair drug test works because any drug that is ingested will circulate in the bloodstream. The bloodstream then circulates through an individual’s entire body, including the scalp where hair follicles are nourished. Subsequently, trace amounts of the ingested drug become trapped in the cortex of the hair follicle and remain there as the hair grows out.

For this reason, a hair drug test can be administered to determine history of drug use because long after the drug has left the bloodstream, the trace amounts remain in the hair follicle. Hair grows at a rate of approximately ½ inch a month and the presence of these chemicals cannot be washed out or stripped away. The only way their presence can be removed is by cutting the hair. Depending on the length of the hair strand, the use of a drug can be detected even a year after use.

The Radioimmunoassay hair drug test provides more detailed information, including history of drug use and even quantities of certain drugs used, than any other form of drug testing. Drug abuse is more accurately detected through hair drug tests than through urine or blood collected drug tests. The only feasible way to pass a hair drug test is to shave the scalp completely, removing all hair containing traces of previously ingested drugs.