How Does a Hair Drug Test Work?
Hair follicle testing, or what most call a hair drug test, detects illicit drugs, alcohol, or date rape drugs in a person's system. The test can identify substances like marijuana, cocaine, methamphetamine, ecstasy, phencyclidine (PCP), and opiates such as morphine.
The accuracy of the results is high, covering up to 90 days of drug use, and the sample collection process is easy to observe, minimizing the possibility of sample tampering, which is common with urine testing.
Hair samples about an inch and a half long are collected, representing three months of growth. The drug concentration in the hair increases as it grows, with the drug closest to the scalp indicating recent drug use. A positive test result usually requires at least three instances of drug use. This method is reliable since there is no way to manipulate the sample once it has been taken.
- Answered by: Andrew David Easler, Esq.
- Published: 10/05/2014
- Updated: 03/14/2023
We are an education company, not a law firm. The information and content we provide is for general informational purposes only and does not constitute legal advice. We make no representations, warranties, or guarantees regarding the accuracy, completeness, or applicability of the content. It is important to always consult with a qualified attorney for specific legal counsel pertaining to your individual circumstances.
Mock Collections for DOT Breath Alcohol Technicians (BAT)
DOT Oral Fluid Collector Train-the-Trainer
Non-DOT Hair Collector Basic Proficiency Training
Non-DOT Urine Specimen Collection Initial Proficiency Training
DOT Breath Alcohol Technician Basic Proficiency Training
DOT Urine Specimen Collector Basic Proficiency Training
DOT Oral Fluid Collector Training
FAA Reasonable Suspicion Training for Supervisors
Training on New York's Workplace Drug Testing Laws
Training on California Workplace Drug Testing Laws
Non-DOT Urine Specimen Collector Train-the-Trainer
Training on Texas Workplace Drug Testing Laws