how many months does drug hair testing go back?

Answer 1

Hello, First of all I'm a Specialty Tech in a Toxicology lab
Second:
Drugs take at least 2 weeks before they show in the hair. A user must have used at least 3 or more perdominate times for it to be identified in the hair. So if you did one line/puff it won't be in your hair. each 1/2inch of hair represents 1 month of growth. Legally, w/out a court order labs are only able to test up to 1 1/2 inches (3 months) and any drugs used 6-9 months ago will show in your hair at about 2-4 inch length after the first 1 1/2 inch from the root. Your best bet is to keep getting hair trims. Don't shave your head entirely. Cause they will go to underarm, leg, arm, chest and in some cases pubic hair. these listed hairs go back in further... You can use these stripping shampoos bought at the head shops but they will only reduce the levels of drugs in your hair not eliminate them... best of luck
"They begin cutting from the ROOT of your hair not the top and are only able to collect 1 1/2 inches and should trim the lenght past that off".. If they do it any other way they are doing it WRONG and I would ask to speak to the supervisor on duty

Answer 2

Hair drug testing

Hair testing is considered highly accurate and can go back normally 3 months (6 months or longer possible with specialist 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 laboratory can detect. Accredited hair drug testing laboratories, 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.

Additionally, for pre-employment hair testing, the inability to obtain a sample may be grounds for not hiring the individual. Hair Testing labs are regulated by CLIA or SAMHSA (not FDA). There is a growing trend in major companies and law enforcement agencies to utilize hair analysis on account of its efficiency and reputation as the gold standard when considering test accuracy. This technology makes use of radioimmunoassay technology with subsequent confirmation by mass spectrometry.

In recent years, hair testing has been the subject of a number of law suits. Studies have shown that different ethnic groups have different hair structure, potentially leading to false-positives.

Answer 3

It usually goes back about 90 days, sometime up to 6 months though. But most tests just go back 90 days. Do you now that you are getting a hair follicle test? They are not really that common for pre-employment tests or anything like that. Most companies just use urine tests.

Answer 4

Hair grows at 1/8-1/4" per week on average, so 1/2-1" per month. Length of hair sets months.