What Is Ringworm?

Ringworm is a very common skin infection caused by several different species of fungi collectively referred to as tinea. The infection causes scaly, round, itchy patches that develop on various parts of the body, including the scalp, groin, nails, feet and the skin under the beard. Prompt treatment usually clears up most cases within a few weeks.

What Causes Ringworm?

  • Infection by fungi. Exposure to animals (especially cats and dogs) with a fungal infection is one mode of transmission.

Symptoms of Ringworm

  • On the scalp: bald patches and scales
  • On the skin: round, red patches that grow to about one inch across. As the patch radiates outward, the central area heals, leaving a red ring where the infection remains active (hence the name “ringworm”)
  • Under a beard: an itchy, scaling rash
  • On the feet: dry scaling and fissuring of the skin between the toes and on the arch (athlete’s foot)
  • People with athlete’s foot may develop a dermatitis (skin inflammation), possibly allergic, at other sites on the feet or hands. It clears when the fungal infection is fully treated.
  • On the nails: thickened, scaly, rough fingernails or toenails (onychomycosis)
  • On the groin: scaly, red-brown patches, usually on the inner area of the upper thigh (jock itch)
  • Hair loss


  • Do not share hairbrushes, hats, clothing, towels or shoes.
  • Wash your hands thoroughly after handling animals and maintain a good hygiene.
  • Thoroughly dry the feet after taking a bath or shower, and after swimming.
  • Avoid lengthy stays in an overheated, humid environment, like the areas around indoor swimming pools. Warmth, moisture and darkness encourage the growth of fungi.
  • Avoid contact with infected pets as much as possible. Seek prompt veterinary treatment for any skin conditions your pet exhibits.
  • Beauty salons and barbershops should disinfect instruments after use. Be sure that yours does.

Diagnosis of Ringworm

  • Ringworm is suspected by observation of the characteristic red-bordered rash.
  • Direct microscopic examination of the scales obtained after scraping the lesion usually proves the presence of the microorganism. On occasions, a culture of these scrapings is needed.
  • Wood’s lamp (ultraviolet lamp) is used to diagnose ringworm.
  • Wear protective, long sleeved clothing and gloves when handling affected animals or their contaminated environment.

How to Treat Ringworm

  • Ringworm can often be cured with over-the-counter antifungal creams or solutions, especially those containing terbinafine, clotrimazole, miconazole, or ketoconazole. Generally, these are applied once or twice daily; the infection should begin to fade within a week. Continuing treatment for the recommended amount of time will help ensure eradication of the fungus.
  • If over-the-counter treatments fail, a more powerful oral agent may be prescribed. Similarly, infection of the nails or scalp usually requires systemic (oral) treatment.
  • Keep affected areas as clean and dry as possible; talcum or medicated powder may be used.
  • If a fungal infection begins to blister or ooze, apply damp compresses to help clear out the affected areas. Do not break blisters; this can spread the infection.
  • If you have ringworm of the groin area (jock itch), wear cotton underwear and change it more than once a day. If your feet are affected (athlete’s foot), change socks frequently to keep your feet dry.
  • Clotrimazole powder should be applied to the shoes to prevent reinfection of athlete’s foot.
  • Topical shampoo therapy is used especially in longer-haired pets. This therapy removes infected hairs, which are the source of an infection to people or other animals.

When to Call a Doctor

  • Call your doctor to confirm the diagnosis, and if symptoms do not improve or if infection continues to spread after several weeks of over-the-counter treatment.
  • Call a doctor if you develop new, unexplained symptoms, which may be side effects from the medications used to treat ringworm.
  • Call your doctor if you suspect scalp ringworm.


Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference

Simeon Margolis, M.D., Ph.D., Medical Editor

Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at Healthcommunities.com

Published: 30 Aug 2011

Last Modified: 24 Feb 2015