Hair Drug Test Detection Windows and Accurate Results

What is a hair drug test?

A hair drug test is a laboratory analysis that detects drug metabolites deposited in hair strands. Unlike urine or saliva tests, it identifies drug use over a longer period, usually up to 90 days. The test involves collecting a small sample of hair, usually from the scalp, which is then sent to one of five national lab networks for analysis: Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, or ExperTox. Every non-negative result undergoes review by a certified Medical Review Officer to ensure accuracy and compliance with regulations.

AMH Nationwide directs the requester to a certified collection site; there is no online ordering. Call (877) 731-6362 to arrange testing.

How far back does a hair drug test go back?

A hair drug test typically detects drug use within the past 90 days. This is because hair grows approximately one half inch per month, and labs often analyze the most recent 1.5 inches of hair closest to the scalp. The test can reveal drug metabolites embedded in the hair shaft, reflecting cumulative use rather than recent or single use. This long detection window makes it suitable for employment screening, legal cases, and probation monitoring.

For specific cases, detection windows might vary slightly based on hair length and testing panel. Contact AMH at (877) 731-6362 for detailed information.

What drugs can be detected in a hair drug test?

Hair follicle drug tests detect a broad range of substances by identifying drug metabolites in hair strands. Commonly screened drugs include:

The exact drugs included depend on the testing panel selected. Call (877) 731-6362 to confirm available panels and pricing.

How is a hair follicle drug test performed?

The test requires collecting about 100-120 strands of hair from the scalp or another body area if scalp hair is unavailable. The sample is sealed and sent to one of the accredited national labs. Testing involves washing the hair to remove external contaminants, then chemically analyzing it for drug metabolites. The entire process complies with strict chain-of-custody protocols to ensure result integrity.

AMH Nationwide does not offer online ordering. To schedule a hair follicle drug test near me or for other questions, call (877) 731-6362.

Is a hair drug test accepted for DOT-regulated testing?

Hair drug testing is not accepted for Department of Transportation (DOT) safety-sensitive positions. DOT regulations require urine drug testing following the federally certified urine protocol under 49 CFR Part 40. Hair follicle tests are used for non-DOT roles where longer detection windows are desired. Employers must follow proper protocols and use authorized laboratories for compliance.

For DOT-regulated testing, contact AMH at (877) 731-6362 to arrange urine drug testing services.

Can a hair drug test detect one-time or passive drug exposure?

Hair drug tests are designed to detect drug metabolites that accumulate in hair after drug use. One-time or very infrequent use may be less likely to produce detectable levels, but it depends on the drug and amount used. Passive exposure, such as being in a smoky environment, generally does not result in a positive hair test because external contaminants are removed during lab washing procedures. The test focuses on internal metabolites incorporated into hair.

For specific concerns about detection limits, call AMH at (877) 731-6362 to discuss testing options.

Common Questions