Hair testing, like oral fluids testing is a relatively new technology when compared to urine testing. As with oral fluid testing, collection is readily observable without any privacy invasion. Unlike oral fluids or urine testing, hair testing has a detection window of up to three months. That said, hair testing has its limitations too. It only tests for five substances:
Hair testing is more costly than either urine drug screening or oral fluid screening. On the plus side, it is nearly impossible to adulterate the specimen so we often recommend hair testing for those individuals whose specimens regularly test “dilute” or “temperature out of range.” Also, hair testing is the only way to determine the pattern of use over an extended period in the recent past and is therefore an extremely useful tool in substance abuse evaluation.
With a three month detection window, hair drug screens offer the largest detection window. The number of substances that can be detected is, however, more limited than the other two options. Often the best use of a hair screen is to establish an initial history of use with a new client. Additionally, a client who continually provides dilute specimens could be successfully screened with a hair test.