--- title: "What is in a hair follicle" description: "What is in a hair follicle reveals drug metabolites detectable for months. AMH Nationwide uses five national labs for precise hair follicle testing. Call (877) 731-6362." author: "AMH Nationwide" date: "2026-08-28" tags: ["what is in a hair follicle"] canonical: "https://amhnationwide.com/what-is-in-a-hair-follicle/" last_updated: "2026-08-28" --- # What is in a hair follicle **By AMH Nationwide** | August 28, 2026 What is in a hair follicle reveals drug metabolites detectable for months. AMH Nationwide uses five national labs for precise hair follicle testing. Call (877) 731-6362. --- What is in a hair follicle includes the hair shaft and embedded drug metabolites that accumulate as hair grows, making hair follicle testing effective for detecting drug use over a 90-day window. AMH Nationwide routes samples through five national labs with certified Medical Review Officers reviewing results. Call (877) 731-6362. BASICS ## What is in a hair follicle in terms of drug testing? A hair follicle contains the hair bulb beneath the scalp where hair cells grow and incorporate substances from the bloodstream. During drug use, metabolites of substances enter the bloodstream and become embedded in the hair shaft as it forms inside the follicle. This allows detection of drug use over time, typically up to 90 days, by analyzing the hair shaft that emerges from the follicle. DETECTION ## How does the composition of a hair follicle affect drug detection? The hair follicle’s structure allows drug metabolites to be deposited in the growing hair. These metabolites are stable within the hair shaft, resisting washing or external contamination. Testing labs analyze the hair shaft, not the follicle tissue itself, to identify parent drugs and metabolites, providing a reliable history of drug use. Hair shaft contains incorporated drug metabolites from bloodstream Metabolites remain stable for months in hair External contamination is minimized by lab washing procedures LAB PROCESS ## What happens to hair follicle samples at the lab? Hair samples collected from the follicle area are sent to one of five national lab networks: [Quest Diagnostics](https://www.questdiagnostics.com/), [LabCorp](https://www.labcorp.com/), Omega Labs, United States Drug Testing Labs, or ExperTox. These labs perform initial screening followed by confirmation testing using advanced techniques like GC-MS or LC-MS/MS. Every non-negative result is reviewed by a certified Medical Review Officer to ensure accuracy and proper interpretation. ORDERING ## How do I get a hair follicle drug test through AMH Nationwide? AMH Nationwide provides the lab order and directs you to a nearby collection site from over 20,000 nationwide. There is no online ordering. Testing is arranged by contacting AMH directly by phone. This ensures proper chain of custody and compliance with regulatory standards. ## Need Hair Follicle Drug Testing? Call AMH Nationwide at (877) 731-6362 to arrange your hair follicle drug test. We provide lab orders and direct you to one of 20,000+ collection sites nationwide. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) TESTING USES ## Who typically orders hair follicle drug tests and why? Hair follicle tests are commonly ordered by employers, courts, [probation](https://amhnationwide.com/hair-follicle-drug-test-probation/) officers, and individuals seeking a long-term drug use history. The test’s 90-day [detection window](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) and resistance to adulteration make it preferred for safety-sensitive and compliance situations where a detailed drug use record is necessary. LIMITATIONS ## Can hair follicle testing detect recent drug use or passive exposure? Hair follicle testing is not effective for detecting very recent drug use within the last few days because drugs take time to incorporate into the hair shaft. Passive exposure is unlikely to produce a positive result since metabolites must be present in the bloodstream to be deposited in hair. Laboratories apply strict washing procedures to avoid false positives from external contamination. REGULATIONS ## Is hair follicle testing regulated for DOT safety-sensitive positions? Hair follicle testing is not accepted for Department of Transportation (DOT) safety-sensitive roles, which require federally certified [urine](https://amhnationwide.com/urine-drug-testing/) testing under [49 CFR Part 40](https://www.transportation.gov/odapc/part40). However, hair testing is used for non-DOT employment drug screening to provide a longer detection window and additional insight into drug use history. AMH Reviewed & Maintained By AMH Nationwide Customer Service AMH Nationwide is BBB A+ accredited and routes every order through Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, or ExperTox, all of which use multiple lab certification agencies and standards such as [SAMHSA](https://www.samhsa.gov/workplace/drug-testing)-aligned laboratory protocols, the ANSI National Accreditation Board for forensic testing and calibration, the College of American Pathologists (CAP), and Clinical Laboratory Improvement Amendments (CLIA). Every non-negative screen is reviewed by a certified Medical Review Officer as part of standard processing before a result is released, and chain-of-custody documentation is maintained on every collection. This page does not constitute medical or legal advice. **Last updated:** July 2026 You May Also Need [Nail Drug TestingNo head or body hair available? A 5-panel fingernail test covers a similar look-back window.Learn more →](https://amhnationwide.com/5-panel-fingernail-drug-test/)[ChildGuard: Environmental ExposureConcerned about a child or loved one? ChildGuard screens for exposure to drugs in their environment.Learn more →](https://amhnationwide.com/5-panel-hair-drug-test-environmental-exposure-childguard/)[Shorten the Detection WindowShortened options like 30 and 60 day hair panels are also available, useful when a urine test’s 1-3 day window is too short.Learn more →](https://amhnationwide.com/30-day-hair-drug-test/)[Hair ETG Alcohol TestAlso need alcohol testing? The hair ETG test screens for alcohol use, and can be added to the same collection.Learn more →](https://amhnationwide.com/etg-and-peth/) Frequently Asked Questions ## Common Questions Hair follicle testing can detect a range of substances including marijuana, cocaine, opiates, amphetamines, PCP, and others depending on the test panel selected. Hair follicle testing typically detects drug use up to 90 days prior, as hair grows approximately 0.5 inches per month and labs usually test a 1.5-inch hair sample. While harsh treatments can affect hair quality, drug metabolites remain embedded in the hair shaft and lab washing protocols remove external contaminants to ensure accurate results. Yes, all non-negative hair follicle test results are reviewed by a certified Medical Review Officer to confirm findings and provide professional interpretation. No, DOT-regulated safety-sensitive testing requires federally certified urine testing under 49 CFR Part 40. Hair testing is used for non-DOT roles. Contact AMH Nationwide by calling (877) 731-6362 to receive a lab order and be directed to a nearby collection site. There is no online ordering. Sources • [SAMHSA – Mandatory Guidelines for Federal Workplace Drug Testing Programs](https://www.samhsa.gov/workplace/drug-testing) • [U.S. DOT – 49 CFR Part 40 – Procedures for Transportation Workplace Drug and Alcohol Testing Programs](https://www.transportation.gov/odapc/part40) • [CDC – National Center for Health Statistics – Drug Use FastStats](https://www.cdc.gov/nchs/fastats/drug-use.htm) • [Quest Diagnostics – Employer Solutions, Hair Testing Methodology](https://www.questdiagnostics.com/) • [LabCorp – Occupational Testing Services](https://www.labcorp.com/) ## Ready to get started? AMH Nationwide provides the lab order and arranges collection nationwide. Every non-negative result reviewed by a certified Medical Review Officer. Call (877) 731-6362 or contact us. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) --- **Need a drug, alcohol, HIV or STD test?** AMH Nationwide is a national lab testing agency operating since 2004, with more than 20,000 collection sites across the United States. Hair, urine, fingernail and blood testing, panels from 5 through 19, for individuals and employers. - Call: (877) 731-6377 - Find a collection site: https://amhnationwide.com/locations/ - Full page: https://amhnationwide.com/what-is-in-a-hair-follicle/