--- title: "How long can drugs be detected in hair" description: "How long can drugs be detected in hair? Hair follicle tests detect drug use up to 90 days. Call (877) 731-6362 for lab-directed testing info." author: "AMH Nationwide" date: "2026-08-28" tags: ["how long can drugs be detected in hair", "how long can drugs be detected in hair | how long can drugs be detected in hair follicle test"] canonical: "https://amhnationwide.com/how-long-can-drugs-be-detected-in-hair/" last_updated: "2026-08-28" --- # How long can drugs be detected in hair **By AMH Nationwide** | August 28, 2026 How long can drugs be detected in hair? Hair follicle tests detect drug use up to 90 days. Call (877) 731-6362 for lab-directed testing info. --- How long can drugs be detected in hair? Hair follicle drug tests can detect drug use for up to 90 days after use. These tests analyze hair samples collected at a certified lab network and reviewed by a Medical Review Officer. For lab-directed hair follicle testing, call (877) 731-6362. [DETECTION WINDOW](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) ## How long can drugs be detected in hair follicle tests? Hair follicle drug tests can detect drug metabolites in the hair shaft for approximately 90 days after drug use. This detection window is longer than [urine](https://amhnationwide.com/urine-drug-testing/) or saliva tests, which typically detect recent use within days. Hair grows about half an inch per month, so a 1.5-inch hair sample represents roughly three months of drug exposure. Laboratories analyze this segment to determine drug use history. Typical detection window: up to 90 days Hair length tested: usually 1.5 inches from the scalp Detection is based on drug metabolites incorporated into hair follicles TESTING PROCESS ## What is involved in hair follicle drug testing? Hair follicle testing requires collection of a small hair sample, usually from the scalp. AMH Nationwide directs the requester 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. The collected hair sample is sent to a certified laboratory where it is analyzed for drug metabolites. Every non-negative result is reviewed by a certified Medical Review Officer to ensure accuracy and proper interpretation. WHO ORDERS ## Who typically orders hair follicle drug tests? Hair follicle tests are commonly ordered by employers for [pre-employment](https://amhnationwide.com/pre-employment-hair-testing/) or ongoing employee drug screening, especially for positions requiring safety-sensitive roles outside of Department of Transportation (DOT) regulations. Courts, [probation](https://amhnationwide.com/hair-follicle-drug-test-probation/) officers, and individual clients may also request hair testing to verify long-term drug use. DOT-regulated testing requires federally certified urine testing under [49 CFR Part 40](https://www.transportation.gov/odapc/part40); hair testing is not accepted for DOT safety-sensitive roles. SCIENTIFIC RELIABILITY ## How reliable are hair follicle drug tests? Hair follicle drug tests provide a reliable detection method with a long detection window. Drug metabolites are incorporated into hair as it grows, making results less susceptible to short-term abstinence or passive exposure. The use of five national lab networks and review by certified Medical Review Officers enhances result accuracy and reduces false positives or negatives. ## Ready to Schedule Hair Follicle Drug Testing? Contact AMH Nationwide to arrange lab-directed hair follicle drug testing through our national lab network. Call (877) 731-6362 for assistance. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) LIMITATIONS ## What are the limitations of hair follicle drug testing? Hair testing does not detect very recent drug use within the past 7 days because drugs take time to incorporate into hair. Environmental contamination or cosmetic hair treatments may affect results but are considered during laboratory analysis and Medical Review Officer review. Detection windows vary by drug type, hair growth rate, and individual metabolism. Does not detect use within past 7 days Potential interference from hair treatments considered Detection window varies by drug and hair characteristics PRICING & ORDERING ## How do I arrange hair follicle drug testing with AMH Nationwide? AMH Nationwide provides the lab order and directs you to a collection site within its five national lab networks. There is no online ordering available. Pricing varies depending on the drug panel selected and detection window required. Call (877) 731-6362 for a quote and to schedule testing. 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 follicle tests can detect a single drug use event but only after about 7 days have passed for the drug to incorporate into the hair. The test reflects drug use over the prior 90 days. Passive exposure is unlikely to cause a positive hair follicle test because the test detects drug metabolites inside the hair shaft, not external contamination. The Medical Review Officer reviews all non-negative results. Since drugs take about 7 days to appear in hair, testing immediately after use may not detect the drug. Waiting at least 7 days ensures accurate detection. No, DOT-regulated safety-sensitive testing requires federally certified urine testing under 49 CFR Part 40. Hair follicle testing is used for non-DOT roles. Hair follicle tests can detect a variety of drugs including marijuana, cocaine, opiates, amphetamines, PCP, and synthetic opioids. Panels vary by request. Hair follicle drug tests are highly accurate when conducted through certified labs and reviewed by Medical Review Officers. They provide a reliable indication of drug use over the past 90 days. 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-can-drugs-be-detected-in-hair/