Hair follicle drug and alcohol testing is becoming more popular among businesses because of its longer look back period. Hair follicle testing can detect substance abuse going back approximately 90 days. When a substance is used, it is absorbed and metabolized into the bloodstream. Hair growth is fed by blood flow; therefore, any used substances and their metabolites will be embedded in the hair. Our hair follicle drug and alcohol testing differentiate between the metabolites and the actual drug so there can be no mistaking the possibility of external contamination as the reason for a positive result. Although there are endless advertisements for shampoos, conditioners, sprays, gels and other gimmicks promising to remove the evidence of substance abuse to "trick" the hair follicle test, those claims are false. Hair follicle collection is completed directly by an examiner, which precludes altering a specimen.