--- title: "Can a hair follicle test go back 12 months" description: "Can a hair follicle test go back 12 months? Hair drug tests typically detect up to 90 days. Learn detection limits. Call (877) 731-6362 for details." author: "AMH Nationwide" date: "2026-08-28" tags: ["can a hair follicle test go back 12 months info"] canonical: "https://amhnationwide.com/can-a-hair-follicle-test-go-back-12-months-info/" last_updated: "2026-08-28" --- # Can a hair follicle test go back 12 months **By AMH Nationwide** | August 28, 2026 Can a hair follicle test go back 12 months? Hair drug tests typically detect up to 90 days. Learn detection limits. Call (877) 731-6362 for details. --- Can a hair follicle test go back 12 months? Hair follicle drug tests generally detect drug use within the past 90 days, not 12 months. Hair grows about half an inch per month, and standard testing analyzes up to 1.5 inches of hair. For longer detection periods, hair length and testing methods vary. Call (877) 731-6362 for lab details and scheduling. [DETECTION WINDOW](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) ## How far back can a hair follicle drug test go? A hair follicle drug test typically detects drug use within the last 90 days. This is because hair grows approximately 0.5 inches per month, and most tests analyze 1.5 inches of hair closest to the scalp. Testing beyond this length is uncommon and less reliable. Longer hair samples can technically be tested to extend the detection window, but labs rarely process beyond 1.5 inches due to decreased accuracy and the potential for external contamination. AMH Nationwide routes collections 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. These labs standardly test up to 1.5 inches of hair to cover about three months of drug history. HAIR TEST BASICS ## How long do drugs stay in hair follicles? Drugs enter the hair follicle from the bloodstream shortly after use and become trapped in the hair shaft as it grows. Because hair grows slowly, drugs remain detectable in hair for months. The typical detection window for most hair drug tests is about 90 days. This period reflects the length of hair tested rather than the actual metabolic clearance of drugs from the body. Hair testing does not detect very recent drug use within the past week because hair near the scalp takes time to grow out. TEST LIMITATIONS ## Can a hair follicle test go back 12 months? Standard hair follicle drug tests cannot reliably detect drug use going back 12 months. The reason is that hair length and testing protocols limit detection to roughly 90 days. While longer hair can be submitted for testing, labs generally do not analyze hair beyond 1.5 inches due to sample variability and external contamination risks. If a longer detection window is needed, alternative testing methods or repeated testing over time might be considered. TESTING PROCESS ## How long does a hair follicle drug test take? After collection at an AMH Nationwide authorized site, hair samples are sent to one of five national labs for analysis. The turnaround time usually ranges from 3 to 5 business days depending on the lab and test panel. Every non-negative hair drug test is reviewed by a certified Medical Review Officer (MRO) as part of standard processing to ensure accuracy and reliability. AMH Nationwide does not offer online orders; all testing requires contacting us at (877) 731-6362 to schedule and arrange lab orders. ## Need Accurate Hair Follicle Drug Testing? Contact AMH Nationwide to schedule hair follicle testing through major accredited labs. Call (877) 731-6362 to arrange your lab order and collection. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) WHO USES HAIR TESTING ## Who typically orders hair follicle drug tests? Employers, courts, [probation](https://amhnationwide.com/hair-follicle-drug-test-probation/) officers, and individuals use hair follicle drug tests to detect drug use over a longer period than [urine](https://amhnationwide.com/urine-drug-testing/) tests. Hair testing is often preferred for non-DOT safety-sensitive roles because the Department of Transportation requires federally certified urine testing protocols for DOT-regulated positions. AMH Nationwide provides lab orders and directs requesters to collection sites nationwide, working with major labs to ensure reliable results. HAIR VS URINE TESTING ## How does hair follicle testing compare to urine drug testing? Hair follicle testing detects drug use over approximately 90 days, whereas urine testing typically detects recent use within 1 to 4 days depending on the drug. Urine tests are federally certified for DOT safety-sensitive positions under [49 CFR Part 40](https://www.transportation.gov/odapc/part40), while hair tests are mainly used for non-DOT roles due to longer detection windows. Hair testing is less invasive and harder to adulterate but cannot detect very recent drug use, unlike urine 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 No. Standard hair follicle tests analyze up to 1.5 inches of hair, representing about 90 days of drug use. Detection beyond this timeframe is not reliable. Labs typically require at least 1.5 inches of hair from the scalp to test for drugs, reflecting approximately three months of growth. No. Hair testing generally cannot detect drug use within the past 5 to 7 days because the hair containing the drug has not yet grown out from the scalp. No. DOT-regulated safety-sensitive positions require urine drug testing under federally certified protocols. Hair tests are used for non-DOT roles. Hair follicle tests can detect many drugs including marijuana, cocaine, opiates, amphetamines, and PCP, depending on the panel ordered by the requester. All non-negative hair test results are reviewed by a certified Medical Review Officer to confirm findings before reporting to the requester. 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/can-a-hair-follicle-test-go-back-12-months-info/