KOH Staining, Nail

KOH (Potassium hydroxide) staining is a simple, non-invasive test that helps diagnose fungal infections of the nails.  Nail clippings or scrapings are collected from the affected area and examined for signs of fungal infections under a microscope.

A KOH test is recommended for individuals with symptoms of fungal infections of the nails.

A KOH test does not explicitly identify the type of fungus; it only shows that fungus is present. In most cases, knowing precisely the fungus causing the infection may not be necessary. The doctor can make an informed judgment and prescribe treatment.

This test is recommended for individuals who

• have discolored, thickened, or brittle nails suggestive of a fungal infection,
• are at a higher risk due to factors such as diabetes, immunosuppression, or previous fungal infections,
• require confirmation of fungal infection for appropriate treatment, or
• need monitoring during or after antifungal therapy.