--- title: "How far back can a hair sample drug test go" description: "Discover how far back a hair sample drug test can go for reliable drug detection. Learn detection windows and testing details. Call (877) 731-6362 today." author: "AMH Nationwide" date: "2026-08-28" tags: ["how far back can a hair sample drug test go"] canonical: "https://amhnationwide.com/how-far-back-can-a-hair-sample-drug-test-go/" last_updated: "2026-08-28" --- # How far back can a hair sample drug test go **By AMH Nationwide** | August 28, 2026 Discover how far back a hair sample drug test can go for reliable drug detection. Learn detection windows and testing details. Call (877) 731-6362 today. --- How far back can a hair sample drug test go? Hair drug testing typically detects drug use within the past 90 days, providing a longer detection window than urine or saliva tests. This method is reliable for employers, courts, and individuals needing extended drug use history. Call (877) 731-6362 to schedule testing. OVERVIEW ## What is the detection window of a hair sample drug test? The [detection window](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) of a hair sample drug test is generally up to 90 days. Hair testing analyzes a 1.5-inch segment of hair closest to the scalp, representing approximately three months of drug use. This extended window makes hair testing useful for identifying past drug consumption beyond the reach of [urine](https://amhnationwide.com/urine-drug-testing/) or saliva tests, which usually detect recent use within days to weeks. Typical detection window: up to 90 days Hair growth rate: about 0.5 inches per month Tested hair length: usually 1.5 inches from scalp Hair testing is not effective for detecting drug use within the past 7 days since hair needs time to grow above the scalp. LAB PROCESS ## How does AMH Nationwide process hair drug tests? AMH Nationwide routes hair sample drug tests 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. The collected hair sample is analyzed using scientifically validated methods to detect drug metabolites incorporated into the hair shaft as it grows. Every non-negative hair drug screen is reviewed by a certified Medical Review Officer (MRO) to ensure accuracy and interpret results in context. This review helps confirm legitimate medical explanations or prescription use before finalizing results. Labs used: Quest Diagnostics, LabCorp, Omega Labs, USDTL, ExperTox Certified Medical Review Officer reviews all positives Testing detects drug metabolites in hair shaft AMH Nationwide directs clients to a collection site for sample submission; there is no online ordering. Call (877) 731-6362 to arrange testing. TESTING DETAILS ## Which drugs can be detected in a hair sample drug test? Hair drug tests can detect a wide range of substances including: – Amphetamines – Cocaine – Marijuana (THC) – Opiates (heroin, morphine, codeine) – Phencyclidine (PCP) – Benzodiazepines and other prescription medications (depending on panel) The test panel and detection capabilities vary by lab and requester requirements. Some panels also include synthetic opioids and other emerging drugs. Commonly tested drugs: amphetamines, cocaine, marijuana, opiates, PCP Panels vary by request and lab capabilities Prescription medications may be confirmed during MRO review Detection depends on the drugs’ incorporation into hair and the length of hair tested. Contact AMH at (877) 731-6362 for specific panel options and pricing. APPLICATIONS ## Who orders hair sample drug tests and why? Hair drug testing is commonly ordered by employers, courts, [probation](https://amhnationwide.com/hair-follicle-drug-test-probation/) officers, and individuals seeking a longer-term drug use history. It is especially useful when recent use is not the only concern but patterns over months are relevant. Employers use hair testing for [pre-employment](https://amhnationwide.com/pre-employment-hair-testing/) screening or random testing where a longer detection window is required. Courts and probation agencies may require hair tests to monitor compliance over time. Individuals may use hair testing for personal monitoring or legal reasons. Employers for pre-employment and periodic testing Courts and probation for compliance monitoring Individuals for personal or legal drug use history Hair testing is not suitable for Department of Transportation (DOT) safety-sensitive roles, which require federally certified urine testing under [49 CFR Part 40](https://www.transportation.gov/odapc/part40). ## Schedule Your Hair Sample Drug Test Today To learn how far back a hair sample drug test can go for your situation, contact AMH Nationwide. We direct you to a collection site for professional sample collection and lab analysis. Call (877) 731-6362 to get started. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) LIMITATIONS ## Can hair sample drug tests detect one-time or recent drug use? Hair drug tests are less effective at detecting very recent drug use because drugs take approximately 5-7 days to become incorporated into hair above the scalp. One-time or very recent use within this timeframe may not be detected. Additionally, hair testing reflects cumulative drug exposure over weeks to months rather than isolated incidents. Passive exposure to drugs is unlikely to produce positive results at the thresholds used by accredited labs. For recent drug use detection, urine or saliva tests are more appropriate due to their shorter detection windows. Recent use within 5-7 days may not be detected One-time use may be diluted in the 90-day window Passive exposure unlikely to cause positives AMH Nationwide provides guidance on appropriate test types. Call (877) 731-6362 for advice. COMPLIANCE ## Are hair drug tests accepted for DOT-regulated testing? Hair sample drug tests are not accepted for Department of Transportation (DOT) safety-sensitive testing. DOT regulations require urine testing using the federally certified protocol under 49 CFR Part 40. Hair drug testing is used primarily for non-DOT roles or other purposes where extended detection windows are needed. Employers must follow DOT guidelines when testing for safety-sensitive positions. AMH Nationwide provides DOT-compliant urine drug testing and can direct clients accordingly. DOT requires federally certified urine testing (49 CFR Part 40) Hair testing is for non-DOT roles only AMH offers both hair and DOT urine testing Contact AMH at (877) 731-6362 to discuss testing needs and compliance requirements. 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 Hair drug test results typically take 3 to 5 business days after the sample reaches the lab. Complex panels or Medical Review Officer reviews may extend this time slightly. Hair drug tests detect many common drugs such as cocaine, amphetamines, marijuana, and opiates. However, detection depends on the specific test panel ordered by the requester. If hair is too short or unavailable, body hair may be used, but it has a less consistent detection window. In some cases, an alternative test like urine may be recommended. Hair color and type can influence drug incorporation, but accredited labs account for these factors during analysis to ensure accurate results. Passive exposure is unlikely to cause a positive hair drug test because labs use cutoff levels designed to avoid false positives from environmental contact. Costs vary depending on the test panel and detection window. Contact AMH Nationwide at (877) 731-6362 for a personalized quote. 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-can-a-hair-sample-drug-test-go/