--- title: "How far does a hair follicle test go back" description: "How far does a hair follicle test go back? It detects drug use up to 90 days prior. For reliable hair follicle drug testing, call (877) 731-6362 today." author: "AMH Nationwide" date: "2026-08-28" tags: ["how far does a hair follicle test go back", "how far does a hair follicle test go back | how far does hair follicle test go back | how far does hair test go back | how far does a hair test go back | how far does a hair follicle drug test go back | how far does a hair drug test go back | how far does hair follicle drug test go back | how far does a hair follicle test detect drugs"] canonical: "https://amhnationwide.com/how-far-does-a-hair-follicle-test-go-back/" last_updated: "2026-08-28" --- # How far does a hair follicle test go back **By AMH Nationwide** | August 28, 2026 How far does a hair follicle test go back? It detects drug use up to 90 days prior. For reliable hair follicle drug testing, call (877) 731-6362 today. --- How far does a hair follicle test go back? This test can detect drug use typically up to 90 days prior, making it a reliable option for long-term drug detection. Hair follicle drug tests analyze a small hair sample to identify drug metabolites embedded in the hair shaft. Call (877) 731-6362 to schedule a test or learn more. OVERVIEW ## How far does a hair follicle test go back in detecting drug use? A hair follicle test generally detects drug use that occurred within the past 90 days. This is because drugs and their metabolites are deposited into the hair shaft from the bloodstream as hair grows, capturing a historical record of substance use. Hair grows approximately 0.5 inches per month. A standard hair follicle drug test analyzes 1.5 inches of hair closest to the scalp, representing about three months of drug history. This makes it a valuable test for employers, courts, and [probation](https://amhnationwide.com/hair-follicle-drug-test-probation/) officers who need to verify long-term drug abstinence or use. [DETECTION WINDOW](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) ## What is the detection window for a hair follicle drug test? The detection window for a hair follicle drug test is typically up to 90 days after drug use. Unlike [urine](https://amhnationwide.com/urine-drug-testing/) or saliva tests that detect recent use within hours or days, hair testing reveals drug exposure over a longer period. Drugs enter the hair follicle from the bloodstream and become trapped in the hair shaft as it grows. Because hair grows slowly, the test can detect drug metabolites incorporated during the growth period, providing a retrospective timeline of drug intake. Typical detection period: up to 90 days Hair growth rate: about 0.5 inches per month Sample length analyzed: 1.5 inches from the scalp Not effective for detecting use within the past 7 days TESTING PROCESS ## How does the hair follicle drug test process work? The hair follicle test involves collecting a small sample of hair, usually from the crown of the head. The sample is then 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, where it undergoes analysis. The lab extracts drug metabolites from the hair and screens for substances such as marijuana, cocaine, opiates, amphetamines, and PCP. Every non-negative result is reviewed by a certified Medical Review Officer (MRO) as part of the standard processing, ensuring accuracy and reliability. WHO ORDERS IT ## Who typically orders hair follicle drug tests? Hair follicle drug tests are commonly ordered by employers, courts, probation departments, and other organizations requiring long-term drug use verification. They are especially useful for safety-sensitive roles that do not fall under DOT regulations, as DOT testing requires urine tests. Individuals may also request hair follicle testing for personal reasons or legal matters. Because hair testing reflects a longer detection window, it is favored when a comprehensive drug use history is needed rather than recent use only. ## Schedule Your Hair Follicle Drug Test Today To arrange a hair follicle drug test or get more information about detection windows, call (877) 731-6362 or contact us to find a collection site near you. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) LIMITATIONS ## What are the limitations of hair follicle drug tests? Hair follicle tests do not detect very recent drug use within about 7 days, since it takes time for metabolites to be incorporated into the hair shaft. Certain factors such as hair color, cosmetic treatments, and individual hair growth rates can slightly affect test results. However, the five national labs used by AMH Nationwide follow strict protocols to ensure accurate detection. Hair testing 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). COMPARISON ## How does hair follicle testing compare to other drug tests? Hair follicle tests provide a longer detection window compared to urine, saliva, or blood tests, which generally detect recent drug use within hours to days. Urine tests detect drug use typically within 1-4 days, saliva tests within 1-2 days, and blood tests within hours to a day. Hair tests offer a retrospective view up to 90 days, making them effective for long-term monitoring. Below is a comparison table of common drug testing methods and their detection windows: | Test Type | Typical Detection Window | | --- | --- | | Hair Follicle Test | Up to 90 days | | Urine Test | 1-4 days | | Saliva Test | 1-2 days | | Blood Test | Hours to 1 day | 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 cannot detect drug use within the first 7 days after consumption, as it takes time for metabolites to be incorporated into the hair shaft. Chemical treatments like bleaching or dyeing may affect hair structure but labs use methods to minimize impact on test accuracy. Results remain reliable under standard protocols. Yes. The standard 1.5-inch hair sample reflects about 90 days of drug use. Longer hair can provide a longer history, but most tests focus on the most recent 90 days. No. DOT-regulated testing requires federally certified urine tests under 49 CFR Part 40. Hair follicle testing is used for non-DOT roles and other purposes. Hair follicle tests commonly detect marijuana, cocaine, opiates, amphetamines, PCP, and other substances depending on the testing panel. Hair follicle drug tests are highly reliable when conducted by accredited labs with MRO review, such as those used by AMH Nationwide, following strict federal guidelines. 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-does-a-hair-follicle-test-go-back/