Can hair follicle test go back a year
Understanding How Far Back a Hair Follicle Test Can Detect Drug Use
Can hair follicle test go back a year? Hair follicle drug testing typically detects drug use within a 90-day window, not a full year. This makes it a reliable method for identifying long-term drug use but not for a 12-month period. Call (877) 731-6362 for more information about hair follicle testing.
How far back can a hair follicle test detect drug use?
A hair follicle test can detect drug use generally up to 90 days prior to the test date. This is because hair grows approximately half an inch per month, and standard testing analyzes about 1.5 inches of hair closest to the scalp.
Testing beyond 90 days is unreliable because older hair segments are either not collected or do not provide accurate results due to environmental exposure and hair treatments.
What is the hair follicle testing process and how does it detect drugs?
Hair follicle testing involves collecting a small sample of hair from the scalp, usually about 1.5 inches long and the diameter of a pencil. This sample is sent to one of five national lab networks: Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, or ExperTox.
The labs analyze the hair for drug metabolites that become embedded in the hair shaft from the bloodstream during hair growth. Every non-negative screen undergoes review by a certified Medical Review Officer (MRO) to confirm results.
Can a hair follicle test reliably detect drug use from a year ago?
No, hair follicle tests cannot reliably detect drug use from a full year ago. The standard length of hair tested corresponds to approximately three months of growth.
Testing longer hair segments is possible but is not standard practice because hair older than 90 days may be degraded or affected by environmental factors, reducing test reliability.
How does hair follicle testing compare to other drug detection methods for long-term use?
| Testing Method | Detection Window |
|---|---|
| Hair Follicle Test | Up to 90 days |
| Urine Test | 1 to 7 days depending on substance |
| Blood Test | Hours to 2 days |
| Saliva Test | 1 to 3 days |
Hair follicle testing offers the longest detection window among common drug tests, making it useful for employer, court, or probation monitoring of long-term drug use.
Need a Hair Follicle Drug Test?
Call (877) 731-6362 to schedule a hair follicle test or get detailed information about detection windows, testing procedures, and lab locations.
Is hair follicle testing accepted for DOT-regulated safety-sensitive positions?
No, hair follicle testing is not accepted for Department of Transportation (DOT) regulated safety-sensitive testing. DOT requires the federally certified urine testing protocol under 49 CFR Part 40.
Hair testing is used primarily for non-DOT roles where longer detection windows are desired.
How do I arrange a hair follicle test through AMH Nationwide?
AMH Nationwide provides the lab order and directs you to one of over 20,000 nationwide collection sites affiliated with our five national lab networks: Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, and ExperTox.
There is no online ordering for hair follicle tests. To schedule or inquire about testing, call (877) 731-6362 for assistance.
Common Questions
No, hair follicle tests typically detect drug use within the past 90 days. Hair older than this is not reliably tested.
Standard hair follicle tests require about 1.5 inches of hair closest to the scalp to cover roughly 90 days of drug use.
Yes, certain hair treatments can reduce drug metabolite concentrations but labs and Medical Review Officers account for this in result interpretation.
No, DOT requires urine testing under 49 CFR Part 40. Hair follicle testing is used for non-DOT testing.
Passive exposure is unlikely to cause a positive hair test because metabolites must enter the bloodstream and incorporate into hair.
Call (877) 731-6362 to arrange testing. AMH provides the lab order and directs you to a nearby collection site.
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.