--- title: "Hair Follicle Drug Test: Detection Window | AMH Nationwide" description: "Understand the hair follicle drug test detection window and how it reveals drug use up to 90 days. Learn factors affecting detection. Call (877) 731-6362." author: "AMH Nationwide" date: "2026-08-27" tags: ["Hair follicle drug test detection window", "Hair Follicle"] canonical: "https://amhnationwide.com/hair-follicle-drug-test-detection-window/" last_updated: "2026-08-27" --- # Hair Follicle Drug Test: Detection Window | AMH Nationwide **By AMH Nationwide** | August 27, 2026 Understand the hair follicle drug test detection window and how it reveals drug use up to 90 days. Learn factors affecting detection. Call (877) 731-6362. --- The hair follicle drug test detection window typically covers up to 90 days, making it effective for identifying past drug use over a longer period than other tests. This test analyzes drug metabolites trapped in hair shafts, reflecting usage history. Call (877) 731-6362 to schedule a lab collection or for more details. OVERVIEW ## What is the hair follicle drug test detection window? The hair follicle drug test detection window refers to the period during which drug use can be identified by analyzing hair samples. This test detects drug metabolites embedded in the hair shaft, reflecting drug consumption typically up to 90 days prior to collection. Unlike [urine](https://amhnationwide.com/urine-drug-testing/) or saliva tests, it does not detect very recent use but provides a longer-term usage history. SCIENCE ## How does the hair follicle drug test detect drugs over time? Hair follicle drug tests detect drugs by identifying metabolites deposited in the hair follicle’s growing cells. As hair grows approximately 0.5 inches per month, a 1.5-inch sample can represent about 90 days of drug intake. Metabolites enter the hair follicle via the bloodstream and remain trapped in the hair shaft as it grows, creating a chronological record of drug exposure. TIMEFRAME ## What is the typical detection window for hair follicle drug tests? The typical detection window for hair follicle drug tests is up to 90 days. This window depends on the length of hair collected, usually 1.5 inches from the scalp. Drugs used within the past 7 days may not be detected due to the time needed for hair growth to carry metabolites above the scalp surface. Standard sample length: 1.5 inches Average hair growth: 0.5 inches/month Detection period: up to 90 days Does not detect use within the past week FACTORS ## What factors influence the hair follicle drug test detection window? Several factors can affect the detection window of a hair follicle drug test. Hair growth rate varies by individual, which might shorten or lengthen the effective detection period. Hair treatments such as bleaching or dyeing may reduce metabolite concentration, potentially impacting detection. Additionally, the type of drug, frequency of use, and sample size influence detection accuracy. Individual hair growth rate variability Hair treatments (bleaching, dyeing, perming) Drug type and frequency of use Sample length and collection site ## Need to Know Your Hair Follicle Drug Test Detection Window? Contact AMH Nationwide to schedule your test or get detailed information. Call (877) 731-6362 for assistance. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) PROCESS ## How is the hair follicle drug test performed and processed? The hair follicle drug test is performed by collecting a small sample of hair, usually 1.5 inches long, from close to the scalp. AMH Nationwide directs the requester to a collection site within its network of five national labs: [Quest Diagnostics](https://www.questdiagnostics.com/), [LabCorp](https://www.labcorp.com/), Omega Labs, United States Drug Testing Labs, and ExperTox. After collection, the sample is analyzed for drug metabolites. Non-negative results are reviewed by a certified Medical Review Officer as part of standard procedure. LIMITATIONS ## What are the limitations of the hair follicle drug test detection window? The hair follicle drug test does not detect very recent drug use within the past 7 days due to the time required for metabolites to become embedded in hair above the scalp. External contamination and cosmetic hair treatments may affect test results. The test is not used for DOT-regulated safety-sensitive testing, which requires federally certified urine protocols under [49 CFR Part 40](https://www.transportation.gov/odapc/part40). 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 A hair follicle drug test typically detects drug use up to 90 days prior to collection, depending on hair length and growth rate. Because hair grows about 0.5 inches per month, it takes several days for drug metabolites to appear in the hair above the scalp where samples are collected. Yes, treatments like bleaching or dyeing can reduce metabolite concentrations in hair, potentially affecting detection accuracy. AMH Nationwide routes hair follicle drug tests through Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, and ExperTox. No, DOT-regulated testing requires federally certified urine testing under 49 CFR Part 40; hair tests are for non-DOT roles. AMH Nationwide provides lab orders and directs you to a collection site. Call (877) 731-6362 to arrange your test. 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/hair-follicle-drug-test-detection-window/