Exams and Tests

Doctors often can easily recognize ringworm by its ring-shaped rash. Your doctor will probably also look at a skin sample (KOH preparation) under a microscope to confirm that fungus is present.

Tests for ringworm of the skin include:

• A KOH (potassium hydroxide) preparation. This test can help your doctor find out whether a fungus is causing your rash. The doctor will take a sample of your skin by lightly scraping the infected area. The sample is placed on a slide with potassium hydroxide (KOH) solution and gently heated. If fungus cells are present, the doctor can then see them with a microscope.
• A Wood's light exam. This test may be used to see if the rash is caused by a fungus. Your doctor will shine a special light on your skin where you have the rash. Certain kinds of fungi glow under this light.
• A fungal culture (skin culture). This test can identify the type of fungus that is causing your infection. Usually a culture is only done if the diagnosis is difficult or the skin condition is not responding to treatment. This test may take up to 4 weeks, because it takes time for the fungus to grow.

Treatment Overview

Most cases of ringworm of the skin, including jock itch and ringworm of the hand, can be treated with creams or ointments that you put on your skin to kill fungi. These are called topical antifungals. You can get many topical antifungals without a prescription. Brand names include Micatin, Tinactin, Mycelex, and Lamisil.

You may need to take antifungal pills (oral treatment) if the ringworm does not go away after you have tried different topical antifungals or if the infection is widespread. Oral treatments include azoles such as fluconazole (Diflucan), allylamines such as terbinafine (Lamisil), and griseofulvin (Grifulvin V).

Your rash may start to clear up soon after you begin treatment, but it is important to use the medicine exactly as the label or your doctor says. This will help keep the infection from coming back. You will probably need to continue treatment for 2 to 4 weeks.

If not treated, ringworm can spread and the skin can become irritated and painful. Skin blisters and cracks can become infected with bacteria. If this happens, you may need to take antibiotics.

What to think about

You should treat a fungal infection right away. Severe and widespread infections can be hard to treat.