Hair follicle tests are being embraced by drug screening organizations as a more reliable way to test for drugs in a person’s system. This is because while urine and other forms of testing might be easier to sabotage, hair follicles retain evidence of drug use for up to 90 days since last use, unlike urine tests, whose results cannot be trusted after 7 days. For body hair, even longer- sometimes as long as 360 days. Hair follicle testing can also be used to check for not just a single use, but repetitive use of substances over time. Basically, they are much harder to cheat.
When drugs are ingested, they are absorbed by the hair follicles, and later on by the strands themselves- where they can stay for a pretty long time. Also, second hand smoke absorbed by being in the presence of someone who is smoking do not give false positives, so the authenticity of the tests is assured.
A lot of marijuana advocacy sites claim to have methods and shampoo concoctions that can help remove traces from the hair, but these are often fake. Hair follicle tests however, are not able to reveal the date of drug use which is why 1.5 inches of hair is the standard to use. Since hair grows about 0.5 inches monthly, this length, cut from the root indicates 3 months of history, which is the standard testing period for most tests.
If you are taking a hair follicle drug test, you can request for the person taking the sample to cut off and discard any length past 1.5 inches. Otherwise, your results might be showing substances from a very long time ago, which might have unfavourable results for you. If you are being tested on the request of an employer or any other authority other than the police, you have a right to demand this.
There are four major types of hair follicle drug tests which parallel the types of urine sample tests. The 5 Panel Hair Follicle Drug Test checks for use of cocaine, marijuana, PCP, opiates, or amphetamines which include ecstasy, meth and molly in the past 3 months. This test can be further extended to check for opiates in more detail, in which abuse of substances like Oxycontin would show up. The 9 panel follicle test is an expansion of the 5 panel test to look for even more classes of drugs, including Benzodiapenes like Xanax. The 12 panel follicle test is the most comprehensive type and also has the longest detection window. It tests for all 12 major classes of drugs, including prescription drugs. There is also a test type which focuses on alcohol. Commonly ordered by courts, spouses or family members, the alcohol hair follicle test is used to detect if someone has ingested alcohol over the past 90 days.
When head hair is not available, underarm, leg and chest hair can be used. Occasionally, beard hair too. For bald people, these options can be used. In a situation where they are not available however, the test cannot be administered. Other factors that can affect results include the type of drugs used, potency, amount and individual metabolism.