Hair Drug Testing
Hair testing is quite accurate and can go back normally 3 months (6 months or longer possible with specialty tests), showing any drugs of abuse used in the detection window. As hair grows out, any drugs used are encased in the hair shaft, so the longer the hair, the longer back in the individual's drug history the lab can detect. Accredited hair drug testing labs, however, only use hair within about 2.5–4 cm of the scalp, and discard the rest. With head hair each 0.5 inch (1.27 cm) corresponds to about 30 days. This limits the detection history to about 90 days, depending upon the rate at which the individual's hair grows. Some people attempt to circumvent this through shaving their heads. In the absence of the required amount of hair on the scalp, body hair can be used as an acceptable substitute.
Extended Opiates Hair Drug Test
Hair Drug Test Kit