How far back can a hair test detect drugs
How Far Back Can a Hair Test Detect Drugs for Reliable Results
How far back can a hair test detect drugs? Hair drug testing can identify drug use typically up to 90 days prior to collection. This method analyzes hair follicles to reveal past substance use with high accuracy. AMH Nationwide directs collections to top labs and reviews all results with certified Medical Review Officers. Call (877) 731-6362.
How far back can a hair follicle drug test detect drugs?
A hair follicle drug test can generally detect drug use for up to 90 days before the test date. This is because drugs and their metabolites become trapped in the hair shaft as it grows, providing a historical record of substance use.
Hair grows approximately half an inch per month. Standard testing analyzes about 1.5 inches of hair closest to the scalp, covering roughly a three-month period.
How does a hair follicle drug test work to detect past drug use?
The hair follicle drug test works by analyzing the hair shaft for traces of drugs and their metabolites. When a person uses drugs, these substances enter the bloodstream and are deposited into the growing hair cells.
As hair grows, these drug traces become part of the hair structure, allowing labs to detect past drug use over an extended period compared to urine or saliva tests.
Which labs process hair follicle drug tests for AMH Nationwide?
AMH Nationwide routes hair follicle drug test collections through five national lab networks: Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, and ExperTox.
Each lab follows strict protocols and submits all non-negative results for review by a certified Medical Review Officer to ensure accuracy and compliance.
Are there limitations to how far back a hair follicle test can detect drugs?
While hair follicle tests can detect drug use up to 90 days prior, factors such as hair length, hair growth rate, and cosmetic treatments can affect results.
Shorter hair or shaved heads may limit the detection window. Additionally, passive exposure to drugs does not typically produce a positive result under standard testing protocols.
Need a Hair Follicle Drug Test? Contact AMH Nationwide
Call (877) 731-6362 to schedule your hair follicle drug test through our national network of labs and collection sites. All results are reviewed by certified Medical Review Officers.
Can hair follicle drug tests be used for DOT-regulated safety-sensitive positions?
Hair follicle drug tests are not approved for Department of Transportation (DOT) safety-sensitive roles. DOT regulations require urine testing using federally certified protocols under 49 CFR Part 40.
Hair testing is available for non-DOT roles seeking extended detection windows beyond urine testing.
How do I arrange a hair follicle drug test with AMH Nationwide?
AMH Nationwide provides the lab order and directs the requester to one of over 20,000 nationwide collection sites. There is no online ordering; all test requests must be made by phone.
To schedule a hair follicle drug test, call (877) 731-6362. Pricing varies by test panel and detection window. Contact us for a quote.
Common Questions
Hair testing can detect drug use typically up to 90 days after consumption because drugs deposit in the hair shaft as it grows.
Yes, hair tests can detect even a single use if enough drug metabolites are incorporated into the hair during growth.
Hair color can have a minor effect on drug binding, but labs adjust for this. Hair testing remains reliable across different hair types.
Hair tests detect drug use after about 7-10 days of hair growth post-exposure, so very recent use may not be immediately detectable.
Hair tests provide a longer detection window but do not detect very recent drug use, unlike urine tests which detect recent exposure within days.
Yes, employers can request hair follicle drug testing. AMH Nationwide provides lab orders and directs to collection sites. Call (877) 731-6362 to arrange testing.
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.