--- title: "How far can a hair follicle go back" description: "How far can a hair follicle go back in drug detection? Hair follicle tests detect drug use up to 90 days prior. Call (877) 731-6362 for testing info." author: "AMH Nationwide" date: "2026-08-28" tags: ["how far can a hair follicle go back"] canonical: "https://amhnationwide.com/how-far-can-a-hair-follicle-go-back/" last_updated: "2026-08-28" --- # How far can a hair follicle go back **By AMH Nationwide** | August 28, 2026 How far can a hair follicle go back in drug detection? Hair follicle tests detect drug use up to 90 days prior. Call (877) 731-6362 for testing info. --- How far can a hair follicle go back to detect drug use? Hair follicle testing can detect drug exposure up to approximately 90 days prior to collection. This makes it a reliable method for long-term drug detection. AMH Nationwide routes collections through five national lab networks. Call (877) 731-6362 for details. [DETECTION WINDOW](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) ## How far back can hair follicle drug testing detect drug use? Hair follicle drug testing can detect drug use up to about 90 days prior to the collection date. This detection window is based on the average rate of hair growth, which is approximately 0.5 inches per month. For a standard 1.5-inch hair sample, labs analyze the most recent 90 days of hair growth to detect drug metabolites incorporated into the hair shaft. Longer hair samples can extend the detection window proportionally, but most tests use 1.5 inches to focus on recent use. COLLECTION PROCESS ## How is hair collected and processed for drug testing? Hair samples are collected at authorized collection sites coordinated by AMH Nationwide. The collector cuts a small sample, usually from the crown of the head, close to the scalp. The sample is 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 segment and wash the hair to remove external contamination before chemically analyzing it for drug metabolites. Every non-negative result is reviewed by a certified Medical Review Officer to ensure accuracy and validity. TESTING ACCURACY ## What affects the accuracy of hair follicle drug tests? Accuracy depends on proper sample collection, handling, and lab processing. Hair follicle tests are highly reliable for detecting drug use within the 90-day window. External contamination is minimized by washing protocols in the lab. Passive exposure to drugs generally does not result in a positive test unless exposure is significant. Hair color, cosmetic treatments, and hair type can influence drug incorporation but labs account for these variables during analysis. TEST APPLICATIONS ## Who typically orders hair follicle drug testing and why? Employers, courts, [probation](https://amhnationwide.com/hair-follicle-drug-test-probation/) departments, and individuals use hair follicle testing to verify drug abstinence over several months. DOT-regulated safety-sensitive testing requires federally certified [urine](https://amhnationwide.com/urine-drug-testing/) protocols; hair follicle tests are used primarily for non-DOT roles or broader time-frame detection. Hair testing is effective for monitoring long-term compliance where recent use detection is insufficient. ## Ready to Schedule Hair Follicle Drug Testing? Call (877) 731-6362 to speak with a representative who will help you arrange testing at a convenient collection site. Accurate, certified testing with expert lab networks is available nationwide. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) TEST LIMITATIONS ## Are there limitations to how far a hair follicle test can detect drug use? Hair follicle tests generally do not detect drug use beyond 90 days due to hair growth and shedding cycles. Very short-term or one-time drug use within days before collection may not be detected if the hair has not grown out enough to incorporate metabolites. Hair treatments like bleaching or dyeing can reduce detection sensitivity but do not eliminate it entirely. ORDERING TESTS ## How do I arrange a hair follicle drug test with AMH Nationwide? AMH Nationwide provides lab orders and directs you to a nearby collection site from our network of over 20,000 nationwide locations. There is no online ordering; to arrange testing, call (877) 731-6362 to discuss your needs and obtain a lab order. Pricing varies by test panel and detection window. Contact us for a quote and detailed information. 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 Typically, hair follicle tests detect drug use up to about 90 days prior. Longer detection is limited by hair length and natural shedding cycles, so results beyond 90 days are uncommon. Hair color and type can influence drug metabolite incorporation, but labs adjust their analysis to account for these factors. Hair color alone does not prevent detection. Cosmetic treatments may reduce the concentration of drug metabolites in hair but do not entirely eliminate the ability to detect drug use. No. DOT-regulated testing requires federally certified urine testing under [49 CFR Part 40](https://www.transportation.gov/odapc/part40). Hair follicle tests are used for non-DOT roles or when longer detection windows are needed. Labs wash hair samples thoroughly before analysis to remove environmental contaminants. This process helps ensure positive results reflect internal drug use. Call (877) 731-6362 to request a lab order and be directed to a local collection site. AMH does not offer 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/how-far-can-a-hair-follicle-go-back/