--- title: "How long does a hair sample go back" description: "Learn how long does a hair sample go back for drug detection. Understand the timeframe and testing process. Call (877) 731-6362 for details and scheduling." author: "AMH Nationwide" date: "2026-08-28" tags: ["how long does a hair sample go back"] canonical: "https://amhnationwide.com/how-long-does-a-hair-sample-go-back/" last_updated: "2026-08-28" --- # How long does a hair sample go back **By AMH Nationwide** | August 28, 2026 Learn how long does a hair sample go back for drug detection. Understand the timeframe and testing process. Call (877) 731-6362 for details and scheduling. --- How long does a hair sample go back is a common question in drug testing. Hair samples typically provide a detection window of up to 90 days, revealing drug use over a longer period than urine or saliva tests. This makes hair testing valuable for employers, courts, and probation agencies. Call (877) 731-6362 to schedule or learn more. [DETECTION WINDOW](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) ## How long does a hair sample go back for drug detection? A hair sample generally goes back about 90 days for detecting drug use. This period depends on the length of the hair collected, as hair grows approximately 0.5 inches per month. Most drug tests analyze 1.5 inches of hair closest to the scalp, representing roughly three months of drug history. Hair testing detects drug metabolites deposited in the hair shaft from the bloodstream. Because hair retains these metabolites, it provides a longer detection window than [urine](https://amhnationwide.com/urine-drug-testing/) or oral fluid tests, which detect more recent use only. TESTING PROCESS ## What substances can be detected in a hair sample? Hair drug testing can detect a wide range of substances, including: – Amphetamines (including methamphetamine) – Cocaine – Marijuana (THC) – Opiates (such as heroin, morphine, codeine) – Phencyclidine (PCP) – Synthetic opioids (fentanyl and analogs) – Benzodiazepines (in some panels) The exact substances tested depend on the test panel requested by the ordering party. AMH Nationwide routes samples through five national lab networks with extensive drug panels. LAB NETWORKS ## Which labs process hair samples for AMH Nationwide? AMH Nationwide routes hair samples 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 follows strict chain-of-custody and testing protocols to ensure accuracy and reliability. All non-negative hair test results undergo review by a certified Medical Review Officer (MRO) before final reporting. This review helps confirm results and address any legitimate medical explanations for positive findings. WHO ORDERS ## Who orders hair drug testing and why? Hair drug testing is commonly ordered by employers for [pre-employment](https://amhnationwide.com/pre-employment-hair-testing/) screening and ongoing workforce monitoring. Courts and [probation](https://amhnationwide.com/hair-follicle-drug-test-probation/) agencies also use hair testing to monitor compliance over longer periods. Because hair testing provides a 90-day detection window, it is preferred when a longer-term drug use history is required rather than recent use only. Hair tests are not used for DOT-regulated safety-sensitive roles, which require federally certified urine testing protocols under [49 CFR Part 40](https://www.transportation.gov/odapc/part40). ## Schedule Hair Drug Testing with AMH Nationwide To arrange hair drug testing or get detailed information about detection windows and lab procedures, call (877) 731-6362. AMH Nationwide will direct you to a nearby collection site and coordinate testing through national labs. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) COLLECTION ## How is a hair sample collected and processed? Hair collection involves cutting a small sample from the scalp area, typically from the crown or back of the head. The sample length is usually 1.5 inches to represent approximately 90 days of growth. AMH Nationwide directs the requester to a nearby collection site within its network. There is no online ordering; all testing requires a lab order and collection appointment. After collection, the sample is sent to a designated lab for analysis and MRO review. RESULTS ## How long does it take to get hair test results? Hair test results typically take 5 to 7 business days after the lab receives the sample. This includes initial screening, confirmatory testing for non-negative results, and review by a Medical Review Officer. The turnaround time can vary depending on the lab network and test panel complexity. Contact AMH Nationwide at (877) 731-6362 for expected timing based on your specific testing needs. 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 Standard hair drug tests analyze approximately 1.5 inches of hair, which corresponds to about 90 days. Longer hair samples can extend the detection window but are less common and may not be requested by employers or courts. Hair testing detects drug metabolites incorporated into the hair from bloodstream exposure. Passive environmental exposure is unlikely to cause a positive result if standard collection and lab protocols are followed. No. DOT-regulated drug testing requires urine samples collected under federally certified protocols (49 CFR Part 40). Hair testing is used for non-DOT roles requiring longer detection windows. Hair testing can detect [ethyl glucuronide](https://amhnationwide.com/hair-etg-alcohol-test/) (EtG), a biomarker for alcohol consumption, but this test is less common and requires specific panels. Standard hair drug tests focus on drugs of abuse rather than alcohol. Hair testing detects drug use over 90 days, while urine testing typically detects recent use within a few days to a week. Hair testing is preferred when longer-term use history is required. All non-negative hair test results are reviewed by a certified Medical Review Officer (MRO). The MRO evaluates the results and contacts the individual to verify any legitimate medical explanations before final reporting. 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-long-does-a-hair-sample-go-back/