--- title: "How long does weed stay in hair follicle" description: "Learn how long does weed stay in hair follicle with precise THC detection. Understand the science and testing process. Call (877) 731-6362 for expert guidance." author: "AMH Nationwide" date: "2026-08-28" tags: ["how long does weed stay in hair follicle", "how long does weed stay in hair follicle | how long does thc stay in hair | how long does thc stay in hair follicle | how long does marijuana stay in hair | how long does thc stay in the hair | how long does weed stay in a hair follicle | how long does marijuana stay in your hair follicle | how long does weed stay in you hair | how long does weed stay in your hair follicle"] canonical: "https://amhnationwide.com/how-long-does-weed-stay-in-hair-follicle/" last_updated: "2026-08-28" --- # How long does weed stay in hair follicle **By AMH Nationwide** | August 28, 2026 Learn how long does weed stay in hair follicle with precise THC detection. Understand the science and testing process. Call (877) 731-6362 for expert guidance. --- How long does weed stay in hair follicle depends on hair length and growth rate. THC metabolites are typically detectable in hair for up to 90 days. AMH Nationwide processes hair follicle drug tests through five national labs with certified review. Call (877) 731-6362 for collection and testing information. [DETECTION WINDOW](https://amhnationwide.com/hair-follicle-drug-test-detection-window/) ## How long does weed stay in hair follicle? Weed, or marijuana, can be detected in hair follicles for up to 90 days after use. This detection window reflects the time it takes for hair to grow out and incorporate THC metabolites into the hair shaft. Typically, hair grows about 0.5 inches per month, and a standard 1.5 inch hair sample can reveal drug use for approximately three months. Hair follicle testing identifies THC metabolites deposited in the hair from bloodstream exposure after marijuana consumption. The test does not detect recent use within the past week because hair must grow out to carry evidence of drug intake. SCIENTIFIC BASIS ## How does THC stay in hair and what affects detection? THC, the active compound in marijuana, is metabolized by the body and its metabolites enter the bloodstream. These metabolites are deposited into the hair follicle cells during hair formation. Once embedded, the metabolites remain stable in the hair shaft, allowing detection long after use. Factors influencing detection include hair color, thickness, and growth rate. Darker hair may bind more metabolites due to higher melanin content. External contamination is minimized by laboratory washing protocols. Hair treatments like bleaching can reduce detectable levels but do not eliminate them. TESTING PROCESS ## How is a hair follicle drug test for weed conducted? AMH Nationwide coordinates hair follicle drug testing 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. A trained collector obtains approximately 100 strands of hair close to the scalp to capture recent growth. The sample is sent to the lab where it undergoes washing to remove external contaminants, then is analyzed using sophisticated methods like gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-tandem mass spectrometry (LC-MS/MS). All non-negative results are reviewed by a certified Medical Review Officer to ensure accuracy. WHO USES HAIR FOLLICLE TESTING ## Who orders hair follicle drug testing for marijuana? Hair follicle drug testing is commonly used by employers, legal authorities, [probation](https://amhnationwide.com/hair-follicle-drug-test-probation/) officers, and individuals requiring long-term drug use verification. It is preferred for its extended detection window compared to [urine](https://amhnationwide.com/urine-drug-testing/) or saliva tests. DOT-regulated safety-sensitive positions require urine testing under federally certified protocols, but hair testing is used for non-DOT roles and other settings where long-term use history is needed. ## Schedule Your Hair Follicle Drug Test Today Call (877) 731-6362 to arrange hair follicle drug testing for marijuana. AMH Nationwide works with five national labs ensuring accurate, MRO-reviewed results. [Call (877) 731-6362](tel:+18777316362)[Contact Us](https://amhnationwide.com/contact-us/) LIMITATIONS ## Can hair follicle tests detect one-time or passive marijuana exposure? Hair follicle tests are designed to detect repeated or chronic marijuana use rather than a single use. A one-time exposure may not deposit enough THC metabolites to be detected reliably. Passive exposure to marijuana smoke is unlikely to produce a positive hair test because the metabolites must be absorbed systemically and incorporated into the hair follicle from the bloodstream, not just deposited externally. PRICING & ORDERING ## How much does hair follicle drug testing for weed cost and how to get tested? Pricing for hair follicle drug testing varies depending on the test panel and detection window required. AMH Nationwide does not offer online ordering; all tests require a lab order and collection appointment at one of our 20,000+ nationwide collection sites. To arrange testing or get a price quote, call (877) 731-6362. Our staff will direct you to the appropriate collection site and testing lab. 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 THC metabolites typically remain detectable in hair follicles for up to 90 days, depending on hair length and growth rate. No, hair follicle tests usually cannot detect marijuana used within the past 7 days because hair must grow out to carry drug metabolites. Yes, darker hair with more melanin may bind more THC metabolites, potentially affecting detection levels. Passive exposure is unlikely to cause a positive hair test since metabolites must enter the bloodstream and be incorporated into hair follicles. AMH hair follicle tests are processed by Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, and ExperTox. Call (877) 731-6362 to get a lab order and be directed to a nearby collection site for hair follicle drug testing. 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-weed-stay-in-hair-follicle/