Can hair be affected by cross-reacting substances such as over-the-counter medications?

Enzyme-immunoassay antibodies (EIA), similar to those used to test urine, are used for the initial screening test for drugs of abuse in hair; therefore the potential for substances such as over-the-counter medications to cause a false positive screening result does exist. To eliminate the possibility of reporting a false-positive due to cross-reactivity, most of the labs automatically confirm by GC/MS all positive results for methamphetamine, opiates, PCP, cocaine and marijuana.



Keywords: Hair Testing EIA False positives

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