--- title: "How far back will hair drug test go" description: "Learn how far back will hair drug test go with AMH Nationwide. Hair follicle tests detect drug use up to 90 days. Call (877) 731-6362 for testing info." author: "AMH Nationwide" date: "2026-08-28" tags: ["how far back will hair drug test go", "how far back will hair drug test go | how far back can a hair strand drug test go | how far back can a hair follicle test go | how far back can a hair drug test go | how far back can a hair test go | how far back do hair follicle tests go | how far back can a hair follicle drug test go | how far back will a hair follicle drug test go | how far back can hair follicle test go | how far back do hair drug tests go"] canonical: "https://amhnationwide.com/how-far-back-will-hair-drug-test-go/" last_updated: "2026-08-28" --- # How far back will hair drug test go **By AMH Nationwide** | August 28, 2026 Learn how far back will hair drug test go with AMH Nationwide. Hair follicle tests detect drug use up to 90 days. Call (877) 731-6362 for testing info. --- How far back will hair drug test go depends on the length of the hair sample, typically up to 90 days. Hair follicle drug tests analyze drug metabolites embedded in hair shafts, providing a longer detection window than urine tests. Call (877) 731-6362 to arrange testing through AMH Nationwide. [DETECTION WINDOW](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) ## How far back can a hair strand drug test go? A hair strand drug test can detect drug use for approximately 90 days prior to collection. This is because hair grows about half an inch per month, and a standard test analyzes 1.5 inches of hair closest to the scalp. Longer hair samples can extend the detection window proportionally. Hair follicle tests detect drug metabolites deposited in the hair shaft from the bloodstream, making it possible to review drug history over months rather than days. TEST SPECIFICS ## How far back can a hair follicle test go compared to other tests? Hair follicle tests provide a longer detection window than [urine](https://amhnationwide.com/urine-drug-testing/) or saliva tests. While urine tests typically detect recent drug use within 1 to 4 days, hair follicle tests can detect drug metabolites for up to 90 days or more. This extended detection window makes hair follicle testing suitable for employers, courts, and [probation](https://amhnationwide.com/hair-follicle-drug-test-probation/) agencies requiring a comprehensive drug use history. | Test Type | Typical Detection Window | | --- | --- | | Urine Test | 1 to 4 days | | Saliva Test | 1 to 3 days | | Hair Follicle Test | Up to 90 days | LAB PROCESS ## What happens during hair drug testing at AMH Nationwide? AMH Nationwide routes hair drug test specimens 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 analyzes the hair sample for drug metabolites using scientifically validated methods. All non-negative results are reviewed by a certified Medical Review Officer (MRO) to ensure accuracy and proper interpretation. This standard process supports reliable reporting. TESTING PROTOCOLS ## Are hair drug tests regulated differently for DOT and non-DOT roles? DOT-regulated safety-sensitive positions require urine drug testing under the federally certified protocol defined in [49 CFR Part 40](https://www.transportation.gov/odapc/part40). Hair testing is not authorized for DOT drug screening. Hair drug tests are typically used for non-DOT workplace testing, legal cases, or individual requests where a longer detection window is needed. ## Schedule Your Hair Drug Test Today To learn how far back a hair drug test can go for your specific needs, call (877) 731-6362. AMH Nationwide will guide you to a convenient collection site and ensure accurate testing with certified lab networks. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) DETECTION LIMITS ## Can hair drug tests detect one-time or passive drug exposure? Hair drug tests detect drug metabolites incorporated into the hair during active drug use. One-time use can be detected if sufficient drug metabolites are present in the hair sample. Passive exposure is unlikely to produce a positive hair test result because the testing methods differentiate between environmental contamination and actual drug ingestion. ORDERING ## How do I get a hair drug test through AMH Nationwide? AMH Nationwide provides the lab order and directs you to the nearest collection site nationwide. There is no online ordering available. To schedule or inquire about hair drug testing, call (877) 731-6362. Pricing varies by test panel and detection window. Contact AMH Nationwide for a personalized quote and assistance. 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 test typically detects drug use up to 90 days prior to the test date by analyzing 1.5 inches of hair closest to the scalp. Yes, hair drug tests can detect one-time drug use if the drug metabolites are present in the hair sample at detectable levels. No, DOT-regulated testing requires urine drug tests under the federally certified protocol. Hair drug testing is used for non-DOT testing purposes. Passive exposure is unlikely to cause a positive hair drug test because labs differentiate between environmental contamination and drug ingestion. A small sample of hair, typically 1.5 inches from the scalp, is cut from the head. If head hair is unavailable, body hair may be used with some limitations. All non-negative hair drug test results are reviewed by a certified Medical Review Officer to confirm accuracy and interpret findings. 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-back-will-hair-drug-test-go/