--- title: "19-Panel Hair Follicle Drug Test: Detection Window | AMH Nationwide" description: "Understand the 19-panel hair follicle drug test detection window and how it reveals drug use history. Call (877) 731-6362 for lab testing details." author: "AMH Nationwide" date: "2026-08-27" tags: ["19-panel hair follicle drug test detection window"] canonical: "https://amhnationwide.com/19-panel-hair-follicle-drug-test-detection-window/" last_updated: "2026-08-27" --- # 19-Panel Hair Follicle Drug Test: Detection Window | AMH Nationwide **By AMH Nationwide** | August 27, 2026 Understand the 19-panel hair follicle drug test detection window and how it reveals drug use history. Call (877) 731-6362 for lab testing details. --- The 19-panel hair follicle drug test detection window typically covers up to 90 days of drug use history. This test analyzes hair samples to detect multiple substances over an extended period, making it useful for long-term drug screening. Call (877) 731-6362 to schedule a test or learn more. OVERVIEW ## What is the detection window for a 19-panel hair follicle drug test? The 19-panel hair follicle drug test [detection window](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) generally spans up to 90 days from the date of collection. This test examines a small hair sample, usually 1.5 inches in length, representing approximately three months of hair growth. Drugs and their metabolites are deposited in the hair shaft from the bloodstream, allowing detection of past use over this extended period. SCIENCE ## How does the 19-panel hair follicle drug test detect drug use over time? Drugs enter the bloodstream after use and are incorporated into the hair follicle during hair formation. As hair grows about half an inch per month, a 1.5-inch hair sample reflects roughly 90 days of drug exposure. The test uses advanced laboratory techniques to identify drug metabolites trapped inside the hair shaft, which remain stable and are not affected by external washing. FACTORS ## What factors can affect the 19-panel hair follicle drug test detection window? Several factors influence the detection window of this test: Hair length and growth rate: Shorter hair or slower growth reduces the detectable period. Hair treatments: Bleaching, dyeing, or perming can reduce metabolite concentrations. Frequency and amount of drug use: Occasional use may be harder to detect than chronic use. Biological differences: Hair color and individual metabolism can affect drug incorporation. Environmental exposure generally does not affect results due to metabolites being inside the hair shaft. Hair length: standard 1.5 inches covers about 90 days Hair treatments: may shorten effective detection Use patterns: heavy use increases detection likelihood Metabolism and hair type: can alter metabolite levels PRACTICAL ## Who typically orders a 19-panel hair follicle drug test and why? Employers use the 19-panel hair follicle drug test to assess long-term drug use history for safety-sensitive or non-DOT regulated positions. Legal and [probation](https://amhnationwide.com/hair-follicle-drug-test-probation/) agencies may also require this test to monitor abstinence over months. The extended detection window provides a broader view than [urine](https://amhnationwide.com/urine-drug-testing/) or saliva tests, making it suited for situations where past drug use verification is critical. ## Need a 19-Panel Hair Follicle Drug Test? Contact AMH Nationwide to arrange testing through our national lab networks. Call (877) 731-6362 for assistance. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) PROCESS ## How is the 19-panel hair follicle drug test collected and processed? AMH Nationwide directs clients to one of five national lab networks for collection: [Quest Diagnostics](https://www.questdiagnostics.com/), [LabCorp](https://www.labcorp.com/), Omega Labs, United States Drug Testing Labs, or ExperTox. A trained collector cuts a small sample of hair close to the scalp. The sample is sent to the lab for analysis. Every non-negative result is reviewed by a certified Medical Review Officer as part of standard procedure. LIMITATIONS ## What are the limitations of the 19-panel hair follicle drug test detection window? While the test can detect drug use up to 90 days prior, it does not identify recent use within the past 7 days due to the time needed for hair growth to incorporate metabolites. Additionally, very short or shaved hair may limit the detection window. The test is not used for DOT-regulated safety-sensitive roles, which require urine testing under federal guidelines. 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 This test can detect drug use up to approximately 90 days prior to collection by analyzing a 1.5-inch hair sample. Yes, treatments like bleaching or dyeing can reduce drug metabolite levels in hair, potentially shortening the detection window. No, it typically cannot detect drug use within the past 7 days since hair needs time to grow and incorporate metabolites. All non-negative results are reviewed by a certified Medical Review Officer as part of the standard testing process. No, DOT testing requires federally certified urine testing under [49 CFR Part 40](https://www.transportation.gov/odapc/part40). Hair follicle tests are for non-DOT roles. Call (877) 731-6362 to coordinate testing at one of our national lab networks including Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, or ExperTox. 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/19-panel-hair-follicle-drug-test-detection-window/