How long does thc stay in your hair sample
How Long Does THC Stay in Your Hair Sample for Reliable Drug Testing
How long does THC stay in your hair sample depends on hair length and use frequency, typically up to 90 days. Hair testing detects THC metabolites embedded in the hair shaft, offering a longer detection window than urine or blood tests. AMH Nationwide uses five national lab networks for precise results. Call (877) 731-6362.
How long does THC stay in a hair sample?
THC can be detected in a hair sample for up to 90 days after use. Hair testing looks for THC metabolites incorporated into the hair shaft as it grows, making it possible to detect drug use from several weeks to months prior.
The typical detection window is approximately three months because hair grows about half an inch per month, and standard hair drug tests analyze 1.5 inches of hair closest to the scalp.
How long does weed stay in a hair sample compared to other drug tests?
Hair testing provides a longer detection window than urine, blood, or saliva tests, which typically detect THC for days to weeks. Unlike urine tests that detect recent use, hair tests identify patterns of use over months.
This makes hair testing suitable for employers, courts, and probation agencies who need to assess longer-term drug use history.
| Test Type | Approximate THC Detection Window |
|---|---|
| Urine | 3 to 30 days depending on use frequency |
| Blood | Up to 24 hours |
| Saliva | Up to 72 hours |
| Hair | Up to 90 days |
How is THC detected in a hair sample?
Testing for THC in hair samples involves collecting a small hair strand from the scalp area, which is then sent to one of AMH Nationwide’s five national lab networks: Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, and ExperTox.
The labs analyze the hair for THC metabolites, primarily THC-COOH, embedded in the hair shaft. Every non-negative result undergoes review by a certified Medical Review Officer for accuracy and interpretation.
What factors affect how long THC stays in your hair sample?
Several factors influence THC detection in hair samples:
Frequency and amount of cannabis use affect metabolite levels in hair. Regular users typically have higher concentrations and longer detection periods.
Hair color, texture, and cosmetic treatments like bleaching or dyeing can slightly affect test sensitivity but do not prevent detection.
Environmental exposure to cannabis smoke is unlikely to produce a positive hair test because metabolites must be ingested and metabolized.
Schedule a Hair THC Test Today
To arrange hair testing for THC detection with certified lab analysis and Medical Review Officer oversight, call (877) 731-6362 or contact us for more information.
Is hair testing for THC used in DOT-regulated testing?
No, hair testing is not used for Department of Transportation (DOT) regulated drug testing. DOT requires urine testing using the federally certified urine protocol under 49 CFR Part 40.
Hair testing is used primarily for non-DOT safety-sensitive roles or other employment, legal, or probation drug screening programs.
How do I get a hair THC test through AMH Nationwide?
AMH Nationwide facilitates hair THC testing by providing the lab order and directing you to a collection site within our network of over 20,000 nationwide locations.
There is no online ordering of tests. To arrange testing, call (877) 731-6362. Pricing varies by panel and detection window, so contact us for a quote.
Common Questions
A single use of cannabis may be detected in hair if the hair sample is collected at least 7-10 days after use, as it takes time for metabolites to incorporate into the hair shaft. However, detection sensitivity is higher with repeated or chronic use.
Yes, hair length affects the detection window. Standard tests analyze 1.5 inches of hair closest to the scalp, representing about 90 days of growth. Shorter hair samples may reduce the detection period.
Bleaching or dyeing hair can reduce the concentration of THC metabolites but usually does not eliminate them completely. Labs consider hair treatments during result interpretation.
Passive exposure to marijuana smoke is unlikely to produce a positive hair test because THC metabolites must be ingested and metabolized, not just inhaled secondhand.
Results turnaround time varies by lab but typically ranges from 3 to 7 business days after sample collection. Non-negative results receive review by a Medical Review Officer before final reporting.
Yes, hair THC tests are widely accepted in employment drug screening, probation monitoring, and legal cases to assess drug use history over several months.
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.