Do you need to know about the last three months?

While some drug metabolites are not detectable in urine for long periods of time, they can remain embedded in the shaft of hair for months.

We only need a few strands of hair which can be collected without a noticable difference in your hair style. The industry standard is to obtain 1.5 inches of hair beginning at the scalp.  Since hair generally grows one half an inch per month, this specimen can represent a 90-day history.