toggle mobile menu Menu
toggle search menu

Site Navigation

Supplemental

Menu

KOH Preparation

KOH Preparation

Test Overview

Doctors use the KOH preparation test to find out if you have a fungal infection. This kind of infection can happen in various parts of the body, such as the skin, nails, mouth, or vagina.

KOH is the abbreviation for potassium hydroxide, the solution that is used in the test.

Why It Is Done

Your doctor may do a KOH test to find out if you have one of these fungal infections:

How To Prepare

In general, there's nothing you have to do before this test, unless your doctor tells you to.

How It Is Done

A doctor or nurse takes a sample by lightly scraping the infected area. Sometimes the doctor will use a swab.

The sample is then placed on a slide with potassium hydroxide (KOH) solution and is gently heated. This solution slowly dissolves the skin cells but not the fungus. The fungus can then be seen with a microscope. Color stains may be used so that the fungus is easier to see.

How It Feels

You may feel a scraping sensation when the doctor or nurse takes the sample. The scraping takes only a few seconds.

It may be uncomfortable if a sample is scraped from under a fingernail or toenail, or if the area is sore, such as when you have thrush.

Risks

There are no known risks from having this test.

Results

Normal

No evidence of fungus is found in the sample.

Abnormal

Evidence of fungus is found.

Credits

Current as of: May 13, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. Healthwise is a URAC accredited health web site content provider. Privacy Policy. How this information was developed to help you make better health decisions.

© 1995- Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.