How far can a hair follicle go back
How Far Can a Hair Follicle Go Back to Detect Drug Use?
How far can a hair follicle go back to detect drug use? Hair follicle testing can detect drug exposure up to approximately 90 days prior to collection. This makes it a reliable method for long-term drug detection. AMH Nationwide routes collections through five national lab networks. Call (877) 731-6362 for details.
How far back can hair follicle drug testing detect drug use?
Hair follicle drug testing can detect drug use up to about 90 days prior to the collection date. This detection window is based on the average rate of hair growth, which is approximately 0.5 inches per month.
For a standard 1.5-inch hair sample, labs analyze the most recent 90 days of hair growth to detect drug metabolites incorporated into the hair shaft.
Longer hair samples can extend the detection window proportionally, but most tests use 1.5 inches to focus on recent use.
How is hair collected and processed for drug testing?
Hair samples are collected at authorized collection sites coordinated by AMH Nationwide. The collector cuts a small sample, usually from the crown of the head, close to the scalp.
The sample is sent to one of five national lab networks: Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, or ExperTox.
These labs segment and wash the hair to remove external contamination before chemically analyzing it for drug metabolites.
Every non-negative result is reviewed by a certified Medical Review Officer to ensure accuracy and validity.
What affects the accuracy of hair follicle drug tests?
Accuracy depends on proper sample collection, handling, and lab processing. Hair follicle tests are highly reliable for detecting drug use within the 90-day window.
External contamination is minimized by washing protocols in the lab. Passive exposure to drugs generally does not result in a positive test unless exposure is significant.
Hair color, cosmetic treatments, and hair type can influence drug incorporation but labs account for these variables during analysis.
Who typically orders hair follicle drug testing and why?
Employers, courts, probation departments, and individuals use hair follicle testing to verify drug abstinence over several months.
DOT-regulated safety-sensitive testing requires federally certified urine protocols; hair follicle tests are used primarily for non-DOT roles or broader time-frame detection.
Hair testing is effective for monitoring long-term compliance where recent use detection is insufficient.
Ready to Schedule Hair Follicle Drug Testing?
Call (877) 731-6362 to speak with a representative who will help you arrange testing at a convenient collection site. Accurate, certified testing with expert lab networks is available nationwide.
Are there limitations to how far a hair follicle test can detect drug use?
Hair follicle tests generally do not detect drug use beyond 90 days due to hair growth and shedding cycles.
Very short-term or one-time drug use within days before collection may not be detected if the hair has not grown out enough to incorporate metabolites.
Hair treatments like bleaching or dyeing can reduce detection sensitivity but do not eliminate it entirely.
How do I arrange a hair follicle drug test with AMH Nationwide?
AMH Nationwide provides lab orders and directs you to a nearby collection site from our network of over 20,000 nationwide locations.
There is no online ordering; to arrange testing, call (877) 731-6362 to discuss your needs and obtain a lab order.
Pricing varies by test panel and detection window. Contact us for a quote and detailed information.
Common Questions
Typically, hair follicle tests detect drug use up to about 90 days prior. Longer detection is limited by hair length and natural shedding cycles, so results beyond 90 days are uncommon.
Hair color and type can influence drug metabolite incorporation, but labs adjust their analysis to account for these factors. Hair color alone does not prevent detection.
Cosmetic treatments may reduce the concentration of drug metabolites in hair but do not entirely eliminate the ability to detect drug use.
No. DOT-regulated testing requires federally certified urine testing under 49 CFR Part 40. Hair follicle tests are used for non-DOT roles or when longer detection windows are needed.
Labs wash hair samples thoroughly before analysis to remove environmental contaminants. This process helps ensure positive results reflect internal drug use.
Call (877) 731-6362 to request a lab order and be directed to a local collection site. AMH does not offer online ordering.
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.