It depends whether they are testing hair from the head or hair for the body. Normally it is 90 days (with a standard test) but it can be up to a year if they test body hair. Check out the link I added for detailed information.
how long ago ??
If you are getting a drug test via hair strand test and you have done something you shouldn't have since the last time you shaved your head, your busted. Your hair is the history of your drug use. In other words, if you have done Ritalin since the last time you cut your hair, considering you shave it bald, it will show up.
how long does it take for heroine to be negative in a hair strand test
Drug stay in your hair for months together.
A hair test will show every drug you have used for the length of your hair.
As long as you have the hair you had when you did the speed.
The hair drug test go back up to 90 days and it takes about a half inch of hair for every 1 month of usage. Also you can check http://www.hairtestfriend.com/shampoo.html The site gave a good cross section of how the toxins get placed in the hair. Also they have a phone counselor. You can call them for consultation and they will answer your questions for free. # 252 489 4754
AnswerUntil the hair that was growing when you took the drug has grown out and been trimmed off by the barber/hairdesser.Answeras long as you have the hair, It shows all your drug use and approximate date.
The drug will be present in the hair follical for many years. The length of the hair only serves to show how long ago the drug was consumed.
You may or may not pass the hair strand test depending on the length of your hair and which strand they take. A long hair will grow in your head for years so something that happened 84 days ago would still be in your hair. On the other hand, if you only took it once 84 days ago, that would probably be so little compared to a total hair that it would be hard to measure.
Could be your hair? One to two inches long? The chlorine can turn dark hair white because of the bleaching effect.
For as long as you have had the hair. If you haven't had a hair cut in three months and did drugs 2 1/2 months ago, the proof will be there.Hair drug testing is one of the important techniques to find presence of drug. Another drug testing includes blood, saliva, urine test etc