List Of Leg Hair Drug Test Time Frame Ideas. Hair follicle drug testing is one of the best ways to assess substance use over a long period. Hair testing should always be head hair if at all possible for best results.

The hair follicle is the pocket, below the scalp, from which the hair strand grows. Our labs detect drug use up to 90 days with head hair. However, the test may not be able to detect drug use that occurred more than 90 days prior to the test.