How far do hair follicles go back
Understanding How Far Hair Follicles Go Back for Drug Detection Benefits Employers and Individuals
How far do hair follicles go back is a common question regarding drug testing. Hair follicle drug tests typically detect substance use up to 90 days prior, reflecting a longer detection window than urine or saliva. Samples are collected and processed through five national lab networks with results reviewed by certified Medical Review Officers. Call (877) 731-6362 for testing guidance.
How far do hair follicles go back in drug testing?
Hair follicle drug testing typically detects drug use within approximately 90 days prior to sample collection. This extended detection window is due to the way drugs are deposited and stored in the hair shaft as hair grows.
Hair grows at an average rate of about 0.5 inches (1.27 cm) per month. Most tests analyze 1.5 inches of hair closest to the scalp, covering roughly three months of drug history. This makes hair follicle testing more effective for detecting past drug use compared to urine or saliva tests, which cover shorter periods.
Employers, courts, and probation agencies often choose hair follicle testing when they require a longer-term overview of substance use. Individual orderers seeking comprehensive drug history can also benefit from this method.
What is the hair follicle drug test collection process?
Hair follicle collection involves cutting a small sample of hair, typically from the crown of the head, close to the scalp. Collection is routed through five national lab networks: Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, and ExperTox. AMH Nationwide coordinates the lab order and directs the requester to a nearby collection site; there is no online ordering available.
The collected hair sample is sent to the selected lab for analysis. Non-negative results undergo review by a certified Medical Review Officer (MRO) to ensure accuracy and proper interpretation. This standard processing step is critical to maintain result integrity.
How reliable is hair follicle testing for detecting past drug use?
Hair follicle testing is highly reliable for detecting drug metabolites deposited in the hair shaft. The method is less susceptible to adulteration or evasion than urine or saliva tests, as hair is difficult to alter after collection.
The five national lab networks used by AMH Nationwide follow stringent protocols aligned with SAMHSA, CAP, and CLIA standards. Additionally, every non-negative screen is reviewed by a certified Medical Review Officer to confirm validity. This multi-step quality assurance ensures accurate and defensible results.
Are there limitations to how far hair follicles can detect drug use?
While hair follicle testing covers approximately 90 days, it cannot detect drug use beyond that period because hair grows out and older hair is not typically collected.
Certain factors may affect detection such as hair length, hair color, cosmetic treatments, and individual hair growth rates. Short or shaved hair may limit available sample length, reducing detection window. Also, drugs incorporated into hair vary with frequency and amount of use.
Understanding these limitations helps employers and individuals set realistic expectations for hair follicle testing outcomes.
Need Accurate Hair Follicle Drug Testing?
AMH Nationwide coordinates collection at over 20,000 sites nationwide with results reviewed by certified Medical Review Officers. Contact us today to arrange testing. Call (877) 731-6362.
How do DOT regulations affect hair follicle drug testing?
DOT-regulated safety-sensitive drug testing requires the federally certified urine protocol under 49 CFR Part 40. Hair follicle testing is not accepted for DOT compliance purposes but may be used for non-DOT roles.
Employers must adhere to these regulations when testing employees in safety-sensitive positions. Hair follicle testing provides a longer detection window but is reserved for roles outside DOT jurisdiction.
What other drug testing options are available besides hair follicle testing?
Other common drug testing matrices include urine, saliva, and blood. Each has different detection windows and uses:
Urine tests detect recent drug use typically within 1-4 days.
Saliva tests detect very recent use, usually within 24-48 hours.
Blood tests detect current impairment but have short detection windows.
Hair follicle tests offer the longest detection window, up to 90 days, useful for historical use assessment.
| Test Type | Detection Window |
|---|---|
| Urine | 1-4 days |
| Saliva | 24-48 hours |
| Blood | Hours to 1 day |
| Hair Follicle | Up to 90 days |
Common Questions
Hair follicle testing can detect one-time drug use, but detection depends on the timing of use relative to hair growth and sample collection. Drugs incorporated into hair typically appear about 5-10 days after use.
Hair color can influence drug binding, with darker hair sometimes showing higher metabolite concentrations. Labs account for this variability during analysis to ensure accurate results.
Passive exposure may result in minimal drug presence in hair. However, confirmatory testing and MRO review help distinguish between passive exposure and actual drug use.
Results typically take 3-5 business days after the lab receives the sample. Non-negative results undergo additional Medical Review Officer evaluation, which may add time.
Yes, many courts and probation agencies use hair follicle testing due to its longer detection window, providing a comprehensive view of drug history.
Hair follicle testing can detect ethyl glucuronide (EtG), a metabolite of alcohol, but this test is less common and typically specialized. Standard hair tests focus on drugs of abuse.
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.