How far back does a hair test go back
How Far Back Does a Hair Test Go Back for Drug Detection Benefits
How far back does a hair test go back? Hair follicle tests detect drug use up to 90 days prior to collection by analyzing hair growth. This method provides a longer detection window than urine or saliva tests. AMH Nationwide uses five national lab networks for accurate results. Call (877) 731-6362.
How far back does a hair follicle test detect drugs?
A hair follicle drug test typically detects drug use up to 90 days prior to the test date. This is because hair grows approximately half an inch per month, and labs analyze about 1.5 inches of hair closest to the scalp.
Hair testing captures a longer detection window than urine or saliva tests, which detect recent or current drug use. This makes hair follicle tests useful for employers, courts, and probation agencies who require a broader drug use history.
What does a hair follicle test detect?
Hair follicle tests detect metabolites of common drugs including marijuana, cocaine, opiates, amphetamines, methamphetamines, PCP, and synthetic opioids. Some labs also test for additional substances depending on the panel ordered.
Because drugs incorporate into the hair shaft from the bloodstream, the test reflects drug use during the hair growth period. External contamination is minimized through lab washing protocols before analysis.
How is hair collected and processed for drug testing?
Hair collection is a simple, non-invasive procedure where a small sample of hair, usually about 100 strands, is cut close to the scalp from the crown of the head.
AMH Nationwide directs the requester to one of five national lab networks: Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, and ExperTox, where certified technicians perform the collection.
Labs wash and prepare the hair sample to remove external contaminants before analyzing it using specialized instrumentation. Any non-negative results are reviewed by a certified Medical Review Officer as part of standard processing.
Are there limitations to how far back a hair drug test can detect?
Yes, hair drug tests generally do not detect drug use within the past 7 days because it takes time for drugs to incorporate into growing hair.
Also, very short hair or shaved heads may limit the ability to collect sufficient hair for testing. In such cases, body hair may be used but offers a less precise timeline.
Hair treatments like bleaching or dyeing can potentially affect test results but labs use methods to mitigate these effects.
Need Accurate Hair Follicle Drug Testing?
Call (877) 731-6362 to schedule your hair drug test through AMH Nationwide. Our process ensures reliable results reviewed by certified Medical Review Officers.
How does hair follicle testing compare to other drug tests in detection periods?
| Test Type | Typical Detection Window |
|---|---|
| Urine Test | 1-4 days for most drugs |
| Saliva Test | 1-2 days |
| Hair Follicle Test | Up to 90 days |
Hair follicle testing offers a significantly longer detection window than urine or saliva testing, making it suitable for monitoring long-term drug use patterns.
How do I arrange a hair follicle drug test with AMH Nationwide?
AMH Nationwide does not offer online ordering. To arrange a hair follicle drug test, call (877) 731-6362 to discuss the testing requirements and be directed to a convenient collection site.
Testing is routed through one of five national lab networks for consistent, reliable results. Pricing varies by panel and detection window. Contact us for a specific quote.
Common Questions
Yes, a single drug use event can be detected if the hair sample covers the growth period when the drug was ingested, typically within the past 90 days.
Hair tests generally cannot detect drug use within the first 7 days after ingestion because the hair containing drug metabolites has not yet grown above the scalp.
Passive exposure is unlikely to cause a positive hair test because labs wash samples to remove external contaminants and analyze drug metabolites incorporated internally.
Non-negative results are reviewed by a certified Medical Review Officer who evaluates potential legitimate medical explanations before confirming results.
Hair treatments may reduce drug metabolite concentrations but laboratories use washing and testing protocols to minimize these effects.
DOT-regulated safety-sensitive testing requires federally certified urine testing under 49 CFR Part 40. Hair testing is used for non-DOT roles.
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.