Hair Follicle Drug Test

Hair follicle drug test is one of the strictest drug test an employer can ask you to take as it can detect drug usage up to 90 days prior the day of the sample collection. As it is relatively expensive method of drug testing, it is less frequently chosen by the employer. 

Hair drug test is popular in employment screening because it can help in determining long-term pattern of abuse and periods of abstinence. Once a drug is used by a person, it enters into their bloodstream is transported to various parts of the body. As part of natural hair growth process, the drug metabolites get absorbed with keratin. Researches have also found that these metabolites are attracted to Melamin and become trapped in the protein structure of the hair. These trapped metabolites are detected by hair drug test, hence the candidate is shown positive.