--- title: "Can a hair follicle test go back 9 months" description: "Can a hair follicle test go back 9 months? Hair drug tests detect substance use up to 90 days typically. Learn more. Call (877) 731-6362." author: "AMH Nationwide" date: "2026-08-28" tags: ["can a hair follicle test go back 9 months"] canonical: "https://amhnationwide.com/can-a-hair-follicle-test-go-back-9-months/" last_updated: "2026-08-28" --- # Can a hair follicle test go back 9 months **By AMH Nationwide** | August 28, 2026 Can a hair follicle test go back 9 months? Hair drug tests detect substance use up to 90 days typically. Learn more. Call (877) 731-6362. --- Can a hair follicle test go back 9 months? Hair follicle drug tests generally detect drug use within the prior 90 days, as hair grows about half an inch per month. Testing beyond 3 months is uncommon and less reliable. AMH Nationwide uses certified labs with strict protocols. Call (877) 731-6362 for detailed testing options. [DETECTION WINDOW](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) ## Can a hair follicle test go back 9 months? A hair follicle test typically detects drug use within the last 90 days, which corresponds to approximately 1.5 inches of hair growth. Since hair grows on average about half an inch per month, testing a standard 1.5-inch hair sample covers roughly three months of drug history. Testing hair samples beyond 3 months, such as 9 months, is not standard practice because hair samples longer than 1.5 inches are less reliable for accurate segmental analysis. Laboratories generally do not test hair segments corresponding to 9 months due to variability in hair growth rates and potential external contamination. Therefore, a hair follicle test cannot reliably go back 9 months to detect drug use. For longer detection windows, other testing methods or repeated testing over time may be necessary. LAB PROCEDURE ## How do AMH Nationwide labs process hair follicle drug tests? AMH Nationwide routes hair follicle tests through five national lab networks: [Quest Diagnostics](https://www.questdiagnostics.com/), [LabCorp](https://www.labcorp.com/), Omega Labs, United States Drug Testing Labs, and ExperTox. Each lab follows strict chain-of-custody and testing protocols. Hair samples are collected at a designated site and sent to the lab, where they undergo immunoassay screening. Any non-negative results are confirmed and reviewed by a certified Medical Review Officer (MRO) to ensure accuracy and interpret findings within clinical context. This process guarantees reliable results for workplace, court, or personal drug testing purposes. TESTING BASICS ## What substances can a hair follicle test detect and for how long? Hair follicle tests commonly detect drugs including cocaine, marijuana (THC), opiates, amphetamines, methamphetamine, phencyclidine (PCP), and others. The detection window is generally up to 90 days. Because substances are deposited in hair follicles from bloodstream circulation, the test reflects drug use during hair growth. Hair color, cosmetic treatments, and hair type can influence detection sensitivity but do not extend the detection window beyond approximately 3 months. Typical detection window: up to 90 days Substances detected: cocaine, THC, opiates, amphetamines, PCP, and more Hair length tested: usually 1.5 inches from scalp Longer hair segments beyond 1.5 inches are not standard for testing DOT REGULATIONS ## Is hair follicle testing accepted for DOT-regulated safety-sensitive positions? No. DOT-regulated drug testing requires [urine](https://amhnationwide.com/urine-drug-testing/) testing under the federally certified urine protocol defined by [49 CFR Part 40](https://www.transportation.gov/odapc/part40). Hair follicle testing is not approved for DOT safety-sensitive roles. Hair testing is used for non-DOT roles when employers or individuals want a longer detection window than urine testing provides. ## Ready to Schedule Your Hair Follicle Drug Test? Contact AMH Nationwide by calling (877) 731-6362 to get directed to a collection site and receive expert assistance with your testing needs. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) TESTING LIMITATIONS ## Can passive exposure or hair treatments affect hair follicle test results? Passive exposure to drugs is unlikely to produce a positive hair follicle test because drugs are incorporated into hair from the bloodstream rather than external contamination. Chemical treatments like bleaching, dyeing, or perming can reduce drug concentrations in hair and potentially cause false negatives, but they do not extend detection windows. Laboratories follow procedures to detect and account for such factors during analysis. ORDERING TESTS ## How do I arrange for a hair follicle drug test through AMH Nationwide? AMH Nationwide provides the lab order and directs you to one of over 20,000 collection sites nationwide. There is no online ordering available. To schedule a hair follicle test, call (877) 731-6362. Pricing varies depending on the test panel and detection window requested. All test results are reviewed by a certified Medical Review Officer as part of standard processing. 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 tests generally detect drug use within approximately 90 days. Testing beyond this period, such as 9 months, is not standard and is less reliable due to hair growth variability and lab limitations. A standard hair follicle test requires about 1.5 inches of hair measured from the scalp, reflecting drug use over roughly the past 90 days. Hair color and type can influence drug concentration levels in hair, but labs adjust for these factors. Hair color does not extend the detection window. No. DOT regulations require urine testing under federally certified protocols. Hair follicle testing is only used for non-DOT purposes. Chemical treatments may reduce drug levels in hair and possibly cause false negatives, but labs are trained to identify and consider these effects during analysis. Call (877) 731-6362 to obtain a lab order and be directed to a nearby collection site. There is no online ordering available. 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/can-a-hair-follicle-test-go-back-9-months/