Causes

Ringworm is common, especially among children. However, it may affect people of all ages. It is caused by a fungus, not a worm like the name suggests.

Many bacteria and fungi live on your body. Some of these are useful, while others can cause infections. Ringworm occurs when a type of fungus called tinea grows and multiplies on your skin.

Ringwork can affect the skin on your:

• Beard -- tinea barbae
• Body -- tinea corporis
• Feet -- tinea pedis (also called athlete's foot)
• Groin area -- tinea cruris (also called jock itch)
• Scalp -- tinea capitis

Ringworm can spread easily from one person to another. You can catch ringworm if you touch someone who has the infection, or if you come into contact with items contaminated by the fungus, such as combs, unwashed clothing, and shower or pool surfaces. You can also catch ringworm from pets that carry the fungus. Cats are common carriers.

The fungus that causes ringworm thrive in warm, moist areas. Ringworm is more likely when you are often wet (such as from sweating) and from minor injuries to your skin, scalp, or nails.

Symptoms

Symptoms of ringworm include:

• Itchy, red, raised, scaly patches that may blister and ooze.
• The patches tend to have sharply-defined edges.
• Red patches are often redder around the outside with normal skin tone in the center. This may look like a ring.

If ringworm affects your hair, you will have bald patches.

If ringworm affects your nails, they will become discolored, thick, and even crumble.

Exams and Tests

Most of the time, your health care provider can diagnose ringworm by looking at your skin. The fungus may glow when your skin is examined with a blue light (called a Wood's lamp) in a dark room.

Tests to confirm the diagnosis may include:

• KOH exam
• Skin biopsy
• Skin culture

Treatment

To care for ringworm:

• Keep your skin clean and dry.
• Apply over-the-counter antifungal or drying powders, lotions, or creams that contain miconazole, clotrimazole, or similar ingredients.
• Don't wear clothing that rubs against and irritates the area.
• Wash sheets and nightclothes every day while you are infected.

Your health care provider may prescribe pills to treat the fungus if you have:

• A severe case of ringworm
• Ringworm that keeps coming back or that lasts for a long time
• Ringworm in your hair

You may need medicines such as ketoconazole, which are stronger than over-the-counter products. You may also need antibiotics to treat skin infections from strep or staph that are caused by scratching the area.

Infected pets also should be treated.

Outlook (Prognosis)

Skin medicine usually treats ringworm within 4 weeks. If your ringworm infection is severe or it does not respond well to self-care, it will usually respond quickly to antifungal pills.

When to Contact a Medical Professional

Call your doctor right away if you have any signs of a bacterial infection, which can result from scratching. These signs include swelling, warm skin, sudden worsening in redness of the patches, red streaking, pus, drainage, and fever.

Call your doctor if:

• You have ringworm on your scalp or beard
• Your skin does not improve after 4 weeks of self-care
• The rash spreads and you have diabetes or a weakened immune system due to disease or certain medications

Prevention

To prevent ringworm:

• Keep your skin and feet clean and dry.
• Shampoo regularly, especially after haircuts.
• Do not share clothing, towels, hairbrushes, combs, headgear, or other personal care items. Such items should be thoroughly cleaned and dried after use.
• Wear sandals or shoes at gyms, lockers, and pools.
• Avoid touching pets with bald spots.

Alternative Names

Dermatophytid; Tinea

References

Superficial fungal infections. In: Habif TP, ed. Clinical Dermatology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2009:chap 13.

Update Date: 5/24/2012

Reviewed by: Kevin Berman, MD, PhD, Atlanta Center for Dermatologic Disease, Atlanta, GA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.