How long are drugs detectable in hair
How Long Are Drugs Detectable in Hair for Reliable Drug Testing
How long are drugs detectable in hair depends on the length of the hair sample, typically up to 90 days. Hair drug testing provides a longer detection window than urine or saliva tests, making it effective for identifying past drug use. AMH Nationwide processes samples through five national lab networks with certified Medical Review Officers. Call (877) 731-6362.
What is the detection window for drugs in hair samples?
The detection window for drugs in hair samples typically extends up to 90 days, depending on the hair length collected. Hair grows approximately 0.5 inches per month, and standard tests analyze about 1.5 inches of hair closest to the scalp. This allows labs to detect drug use over the prior three months.
Hair testing captures drug metabolites deposited in the hair shaft from the bloodstream, providing a longer detection period than urine or saliva tests, which detect recent or current use. This makes hair testing suitable for monitoring long-term drug use patterns.
How does hair drug testing work at AMH Nationwide labs?
At AMH Nationwide, hair samples are collected at authorized sites and routed to one of five national lab networks: Quest Diagnostics, LabCorp, Omega Labs, United States Drug Testing Labs, and ExperTox. These labs use scientifically validated methods to analyze drug metabolites in hair samples.
Every non-negative result is reviewed by a certified Medical Review Officer (MRO) to ensure accuracy and interpret results in the context of medical history and prescription use. This review is standard in all AMH testing processes to maintain reliability and compliance.
Which drugs can be detected in hair and for how long?
Hair testing can detect a variety of drugs including cocaine, marijuana (THC), opiates, amphetamines, methamphetamine, PCP, and synthetic cannabinoids. The detection window for these substances generally covers up to 90 days from the time of use.
Specific detection times can vary slightly by drug and individual factors such as hair color and growth rate, but the standard 1.5 inch sample provides a consistent 3-month window. Hair testing does not detect very recent use within the past week, as it takes time for drugs to incorporate into hair strands.
How does hair drug testing compare to urine and saliva tests?
Hair drug testing offers a longer detection window than urine or saliva tests, which typically detect drug use from hours to a few days prior. This makes hair testing more effective for identifying chronic or past drug use.
Urine tests detect metabolites usually within 1-7 days depending on the drug, while saliva tests detect very recent use within 24-48 hours. Hair testing is less susceptible to short-term fluctuations or attempts to adulterate results.
| Test Type | Detection Window |
|---|---|
| Hair | Up to 90 days |
| Urine | 1-7 days |
| Saliva | 24-48 hours |
Contact AMH Nationwide for Hair Drug Testing
For accurate hair drug tests processed through five national labs and reviewed by certified Medical Review Officers, contact AMH Nationwide. Call (877) 731-6362 to schedule a collection or get a quote.
Are there limitations or factors affecting hair drug detection?
Certain factors can affect hair drug testing results, such as hair color, cosmetic treatments, and environmental exposure. Darker hair may bind more drug metabolites, potentially increasing detection sensitivity.
Cosmetic processes like bleaching or dyeing can reduce detectable drug levels but do not eliminate them. Passive environmental exposure is unlikely to produce positive results due to the specificity of lab analysis. Hair testing cannot detect drug use within the past week because of the time needed for incorporation into hair.
Is hair drug testing accepted for DOT-regulated safety-sensitive positions?
Hair drug testing is not accepted for Department of Transportation (DOT) regulated safety-sensitive positions. DOT requires federally certified urine drug testing under 49 CFR Part 40 protocols.
AMH Nationwide complies with these regulations by providing DOT urine drug testing services through its national lab network. Hair testing is used primarily for non-DOT roles and individual or employer-initiated testing where longer detection windows are required.
Common Questions
Hair drug tests typically detect drug use up to 90 days prior, depending on hair length collected, as hair grows about half an inch per month.
Yes, hair testing can detect one-time or infrequent use within the detection window, but very recent use may not yet be incorporated into the hair.
Hair color can influence drug binding; darker hair may retain more drug metabolites, but labs account for these differences during analysis.
Cosmetic treatments like bleaching or dyeing can reduce drug levels but typically do not prevent detection in a properly conducted test.
No, DOT requires urine drug testing under federal protocols. Hair testing is not accepted for DOT safety-sensitive positions.
Contact AMH Nationwide by calling (877) 731-6362. AMH directs you to a collection site; there is no online ordering available.
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.