Ringworm (Dermatophytosis)

Written by Elly Dock | Published on August 15, 2012
Medically Reviewed by George Krucik, MD

What Is Ringworm (Dermatophytosis)?

Dermatophytosis, more commonly known as as ringworm, is a fungal infection of the skin. Ringworm is a misnomer—the infection is not caused by a worm at all, but by a fungus.

The infection can affect both humans and animals. The fungi that are known to cause dermatophytosis may be present in soil. The infection initially presents itself with red patches on affected areas of the skin and later spreads to other parts of the body. The infection may affect the skin of the scalp, feet, groin, beard, or other areas.

What Causes Ringworm (Dermatophytosis)?

Three different types of fungi can cause this infection: trichophyton, microsporum, and epidermophyton. It is possible that these fungi may live for an extended period of time as spores in soil. Humans and animals can contract ringworm after contact with this soil. The infection can also spread through contact with infected animals or humans. The infection is commonly spread between children and by sharing items that may not be clean.

Who Is at Risk for Ringworm (Dermatophytosis)?

Anyone may develop ringworm, regardless of age. However, the infection is very common among children and people who own cats. You may be more likely to develop dermatophytosis if you are wet or if you have minor skin injuries or abrasions. Using public shower or pool areas may also expose you to the infective fungi. If you are often barefoot, you may develop ringworm of the feet. Additionally, those who often share items such as hairbrushes or unwashed clothing with other people have an increased risk of developing the infection.

Recognizing Ringworm (Dermatophytosis)

Symptoms vary depending on where you are infected. With a skin infection, you may experience the following:

  • red, itchy, scaly, or raised patches
  • patches that develop blisters or begin to ooze
  • patches that may be more red on the outside edges or resemble a ring
  • patches with edges that are defined

If you are experiencing dermatophytosis in your nails, they may become thicker, discolored, or begin to crack. If the scalp is affected, bald patches may develop.

Diagnosing Ringworm (Dermatophytosis)

Your doctor will diagnose ringworm by examining your skin and possibly using a black light to view your skin in the affected area. The fungus will fluoresce (glow) under blacklight. If you’re infected, the areas of the skin where fungus is located will glow.

Additionally, your doctor may confirm a suspected diagnosis of ringworm by requesting some of the following tests:

  • skin biopsy—your doctor will take a sample of your skin or discharge from a blister and will send it to a lab to test it for the presence of fungus
  • KOH exam—your doctor will scrape off a small area of infected skin and place it in potassium hydroxide (KOH). The KOH destroys normal cells and leaves the fungal cells untouched, so they are easy to see under a microscope

Treating Ringworm (Dermatophytosis)


Your doctor may prescribe various medications, depending on the severity of your ringworm infection. Ketoconazole is a prescription cream often used to treat fungal infections. Over-the-counter medications and skin creams may be recommended for use as well. Over-the-counter products may contain clotrimazole, miconazole, or other related ingredients.

Home Care

In addition to prescription and over-the-counter medication, your doctor may recommend that you care for your infection at home by practicing some of the following behaviors, including:

  • avoiding clothing that irritates the infected area
  • washing bedding and clothes every day during infection
  • cleaning and drying your skin regularly

If you have been scratching your skin frequently due to the infection, you may develop a staph or strep infection of the skin. Your doctor may prescribe antibiotics to treat this bacterial infection as you continue treatment for ringworm.

Outlook: How Long Does Ringworm Last?

Skin medication may treat ringworm in four weeks. If you are experiencing severe dermatophytosis that is not responding to over-the-counter treatments or self-care at home, your doctor may prescribe anti-fungal pills to clear up the infection. Most individuals respond positively to treatment.

Preventing Ringworm (Dermatophytosis)

You can prevent ringworm by practicing healthy and hygienic behaviors.

Many infections come from contact with animals and lack of proper hygiene. Remember to wash your hands after interacting with an animal. If you have a pet, keep its living areas clean and disinfected. If you have a weak immune system, avoid any individual or animal that is suspected of having dermatophytosis.

In terms of personal care, you should shower and shampoo your hair regularly. Wear shoes if you shower in community areas. Avoid sharing personal items such as clothing or hairbrushes, as these can carry infective spores. Be sure to keep your feet and skin clean and dry.

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