--- title: "Hair Follicle Drug Test Detection Window" description: "Find hair follicle drug test detection window testing near you with AMH Nationwide's 20,000+ collection sites and certified MRO. Call us now at (877) 731-6362." author: "AMH Nationwide" date: "2026-08-05" tags: ["hair follicle drug test detection window"] canonical: "https://amhnationwide.com/hair-follicle-detection-window-ve-preview/" last_updated: "2026-08-26" --- # Hair Follicle Drug Test Detection Window **By AMH Nationwide** | August 5, 2026 Find hair follicle drug test detection window testing near you with AMH Nationwide's 20,000+ collection sites and certified MRO. Call us now at (877) 731-6362. --- The hair follicle drug test detection window describes how far back a hair sample can reflect drug use, generally up to about 90 days for a standard sample based on average hair growth rates. AMH Nationwide sources this testing through Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, and ExperTox, with 6, 9, and 12 month extended options also available. Call (877) 731-6362 to schedule. How It’s Calculated ## How Is the Detection Window Calculated? Laboratories estimate the hair follicle detection window from average human scalp hair growth, generally cited at roughly half an inch per month. A standard 1.5 inch segment closest to the scalp is collected, which under that average works out to approximately three months, or about 90 days, of growth history represented in a single sample. **Average growth rate:** roughly half an inch of scalp hair per month, a population average rather than an individual guarantee. **Standard segment:** 1.5 inches of hair cut closest to the scalp, representing the most recent growth. **Resulting window:** approximately 90 days of history in a single standard sample. **Variability:** hair growth rate varies by person, hair type, and location on the scalp. This is an average, not a fixed rule for every individual, which is one reason laboratories describe the window as an approximation rather than an exact count of days. AMH Nationwide relies on standardized lab protocols developed and certified by the processing lab rather than an in-house estimate. Recent Use ## What Happens With Very Recent Use? Hair does not surface at the scalp instantly after it forms in the follicle, so drug use in the days immediately before a collection may not yet be reflected in a hair sample taken that same day. This is a well documented limitation of hair testing methodology described by [SAMHSA](https://www.samhsa.gov/workplace/drug-testing) and the reference laboratories AMH Nationwide works with, and it is one reason hair testing is not positioned as a same-day use detector. Because of that lag, hair testing is best understood as a pattern-of-use tool rather than a same-day snapshot. A [urine](https://amhnationwide.com/urine-drug-testing/) or oral fluid test is generally better suited to answer whether someone used a substance in the last day or two; a hair test is better suited to answer whether use has been occurring over recent months. ## Need a longer detection window than 90 days? AMH Nationwide offers 6, 9, and 12 month extended hair test protocols. Call to discuss which window fits your case. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) Extended Windows ## How Do Extended Windows Work? AMH Nationwide offers [extended hair testing](https://amhnationwide.com/extended-hair-testing/) at 6, 9, and 12 month protocols that use a longer hair sample, sectioned into consecutive segments corresponding to roughly 90 days each. Instead of one combined result, a requester can see segment-by-segment findings that may show whether use appears ongoing, decreasing, or absent in more recent segments. | Sample Length | Approximate Window | | --- | --- | | 1.5 inches (standard) | ~90 days | | ~3 inches (segmented) | ~6 months | | ~4.5 inches (segmented) | ~9 months | | ~6 inches (segmented) | ~12 months | What Can Affect the Window ## What Factors Can Affect the Window? Individual hair growth rate, hair treatments such as bleaching or chemical relaxing, and the location of the hair sample can all influence what a hair test can show, according to methodology documentation published by [Quest Diagnostics](https://www.questdiagnostics.com/) and [LabCorp](https://www.labcorp.com/). A certified Medical Review Officer reviews non-negative results as part of standard AMH Nationwide processing. Factors That Can Shift the Window ### What Can Change the Estimate Growth RateVaries by Person Hair TreatmentsBleach / Relaxer Sample LocationScalp vs Body Hair Substance CutoffLab-Specific Level When scalp hair is too short to collect, body hair such as underarm or leg hair can be used, but body hair grows more slowly and less predictably than scalp hair, so the 90 day estimate does not translate directly and the laboratory report may note the difference. By Substance ## Does the Substance Tested Change the Detection Window? The hair-growth-based detection window applies broadly across the substance classes in a standard hair panel, but each substance has its own laboratory cutoff level, meaning very light or infrequent use of some substances may fall below the threshold needed for detection even within the 90 day window. This is a separate question from how far back the test looks. The 90 day estimate describes the historical span the hair sample represents; the cutoff level for each substance determines how much use is needed within that span to register as a positive result. Segmentation ## How Is Extended Hair Testing Segmented in the Lab? For 6, 9, and 12 month extended hair tests, the laboratory divides the longer hair sample into consecutive segments, each representing roughly 90 days of growth, and analyzes each segment separately rather than combining the entire sample into one result. We can also segment the test by 30 and 60 days. This segmented approach is what allows a requester to see whether detected substances appear consistently across several months or only in earlier segments, which can be useful when a court, employer, or program wants to understand a pattern over time rather than a single combined finding for the full sample length. Related Pages ## More on Detection Windows and Testing Options Related AMH Tests Hair Testing Resources & Guides Service by State Service by Audience 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-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/) Detection Window FAQs ## Common Questions About the Detection Window The hair-growth-based window itself does not change, but whether a substance is detectable within that window can depend on how much and how often it was used relative to the laboratory’s cutoff level. Hair growth rate can vary somewhat with age and hair health, which is one reason the 90 day figure is described as an average rather than an exact measurement for every individual. No, the sample length is fixed at the time the lab order is placed; if a longer or shorter detection window is needed, that should be requested during scheduling so the collector can take a longer or shorter segment. No, it is a commonly cited approximation based on average hair growth rates and a standard 1.5 inch sample; individual results can vary based on hair growth speed, treatment history, and the specific substance and amount involved. Cosmetic treatments can slightly reduce detectable drug levels in hair according to laboratory methodology documentation, but they do not reliably eliminate all trace evidence, and unusual results are reviewed by a Medical Review Officer. Call (877) 731-6362 and describe the situation, whether an employer, attorney, court, or personal need, and the team can help match the standard 90 day test or one of the extended 6, 9, or 12 month options. Extended detection window tests generally cost more than the standard 90 day hair test because they require analyzing more hair segments; call for a current quote since AMH Nationwide does not publish fixed nationwide pricing. 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 schedule a hair follicle test? Speak with a specialist or contact us now. Standard and extended detection windows available nationwide. [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/hair-follicle-detection-window-ve-preview/