What Do Hair Drug Tests Check For?

Hair drug tests use a small sample of hair to detect drug use. Hair drug tests can only detect drugs that have already been processed by the body.

Time Frame

• The standard hair drug test can detect drugs that have been in the body for up to 90 days. Hair that is used for hair drugs tests is cut from as close to the scalp as possible.

Function

• Hair drug tests can detect cocaine, marijuana, opiates, methamphetamines and phencyclidine. These are the five classes of drugs that are mandated by the federal government for testing.

Misconceptions

• Many think the hair on your body cannot be used in a hair drug test. This is not true. Body hair grows much more slowly than the hair on your head, which means drugs that have been in your system for up to a year can be detected if using body hair.

Considerations

• Hair drug tests are much more effective in detecting the five drugs mandated by the federal government than are urine drug tests.

Size

• A hair sample must consist of 50 to 70 strands that are at least 1.5 inches in length.