--- title: "How far can a hair drug test go" description: "How far can a hair drug test go? Hair follicle tests detect drug use up to 90 days prior. Reliable lab results reviewed by a Medical Review Officer. Call (877) 731-6362." author: "AMH Nationwide" date: "2026-08-28" tags: ["how far can a hair drug test go", "how far can a hair drug test go | how far can a hair follicle test go | how far can hair drug test go"] canonical: "https://amhnationwide.com/how-far-can-a-hair-drug-test-go/" last_updated: "2026-08-28" --- # How far can a hair drug test go **By AMH Nationwide** | August 28, 2026 How far can a hair drug test go? Hair follicle tests detect drug use up to 90 days prior. Reliable lab results reviewed by a Medical Review Officer. Call (877) 731-6362. --- How far can a hair drug test go? Hair drug tests typically detect drug use up to 90 days prior to collection by analyzing a small hair sample. This makes them effective for long-term substance use screening. AMH Nationwide routes collections through five national lab networks with MRO-reviewed results. Call (877) 731-6362. [DETECTION WINDOW](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) ## How far back can a hair follicle test detect drug use? A hair follicle test can detect drug use up to approximately 90 days before the sample collection date. This is because hair grows about half an inch per month, and labs typically analyze 1.5 inches of hair closest to the scalp. This 90-day window is much longer than [urine](https://amhnationwide.com/urine-drug-testing/) or saliva tests, which detect recent use within days. Hair testing identifies drug metabolites embedded in the hair shaft as it grows. TEST RELIABILITY ## How reliable is a hair drug test for detecting past drug use? Hair drug tests are highly reliable for detecting drug metabolites accumulated over time. The sample is collected under supervised conditions at one of AMH’s 20,000+ nationwide collection sites and analyzed by certified labs including [Quest Diagnostics](https://www.questdiagnostics.com/), [LabCorp](https://www.labcorp.com/), Omega Labs, United States Drug Testing Labs, and ExperTox. All non-negative results undergo review by a certified Medical Review Officer (MRO) to verify findings and rule out possible medical explanations, ensuring accuracy and compliance with federal standards. TEST LIMITATIONS ## Are there limitations to how far a hair drug test can go? While hair tests cover up to 90 days, they do not detect drug use beyond that timeframe because older hair is typically not collected or tested. Also, hair treatments like bleaching or dyeing can sometimes reduce drug metabolite levels but rarely eliminate them completely. Passive exposure to drugs is unlikely to cause a positive result due to the metabolite incorporation process. Hair tests do not detect very recent use within the last 5-7 days since it takes time for hair to grow out from the follicle. WHO ORDERS ## Who typically orders hair follicle drug tests and why? Employers, courts, [probation](https://amhnationwide.com/hair-follicle-drug-test-probation/) officers, and individual clients often order hair follicle tests to verify long-term drug abstinence. This test is preferred in situations requiring a longer detection window than urine or saliva tests, such as [pre-employment](https://amhnationwide.com/pre-employment-hair-testing/) screening, legal cases, or monitoring compliance with treatment programs. ## Need a Hair Drug Test with a 90-Day Detection Window? AMH Nationwide coordinates hair follicle testing through trusted labs with MRO-reviewed results. Contact us to schedule a collection or learn more. Call (877) 731-6362. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) COLLECTION PROCESS ## How is hair collected for a drug test through AMH Nationwide? AMH Nationwide directs test requesters to one of its 20,000+ nationwide collection sites where a trained collector cuts a small sample of hair, usually from the crown area near the scalp. The sample is then sent to one of five national lab networks for analysis. The process follows strict chain-of-custody and testing protocols to ensure integrity and accuracy. DOT AND NON-DOT TESTING ## Is hair testing used for DOT-regulated safety-sensitive positions? Hair drug testing is not approved for DOT-regulated safety-sensitive positions which require federally certified urine testing under [49 CFR Part 40](https://www.transportation.gov/odapc/part40). However, hair testing is commonly used for non-DOT roles where a longer detection window is needed. 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 No, hair drug tests generally detect drug use up to 90 days prior because labs analyze about 1.5 inches of hair closest to the scalp. Hair older than this length is not typically tested. Hair color and type can have minor effects on drug metabolite incorporation, but accredited labs adjust for these factors. Results are reliable across hair colors and textures. Yes, hair tests can detect one-time use if the drug metabolites are present in the hair segment analyzed. However, very recent use within days may not be detected. AMH routes collections to five national lab networks and requires all non-negative screens to be reviewed by a certified Medical Review Officer, ensuring accuracy and compliance. No, AMH Nationwide does not offer online ordering. Test requesters must call (877) 731-6362 to arrange testing and be directed to a collection site. Passive exposure is unlikely to cause a positive hair drug test because drug metabolites must be incorporated into the hair shaft, which typically requires actual drug ingestion. 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-drug-test-go/