Causes, Symptoms and Treatment of Ringworm

How to handle this contagious infection

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Ringworm, also referred to as tinea corporis and tinea capitis, actually isn't caused by a worm, but a fungus. It's a contagious skin infection caused by dermatophytes, which are mold-like parasites that live on the outer layer of the skin. It is a skin infection characterized by itchy, scaly patches on the skin, fingernails and snap.

Tinea corpis is a fungal infection that appears on the scalp, between the toes, in the groin, and in a man's beard, among other places on the body.

"Athlete's foot" refers to ringworm on the feet, and "jock itch" refers to ringworm in the groin.

What Causes Ringworm?

Ringworm occurs when fungi attach and grow on cells that contain keratin, such as those found in the skin and near the hair and fingernails. It is an extremely contagious condition. In fact, just coming in contact with ringworm on someone else's body is all it takes to transmit the fungi.

It affects men and women of all ages rather equally, but children are most susceptible. There are several ways through which people can become infected with ringworm:

  • Having damp skin for an extended period of time (i.e. sweat)
  • Lack of hygiene
  • Minor skin and nail injuries
  • Close contact with others (i.e. sports like wrestling
  • Contact with pets (typically cats and dogs, but other animals including cows, goats, pigs, and horses can also spread ringworm)
  • Contact with contaminated objects and surfaces (i.e. combs, pool surfaces, towels, doorknobs, bedding, locker rooms, showers, clothing)

    Symptoms of Ringworm

    Symptoms of a ringworm infection usually appear 4 to 10 days after exposure to the fungi. Ringworm of the scalp usually appears 10 to 14 days after exposure. Ringworm first appears as a lesion that starts as a flat, scaly patch but develops a defend border and radiates outwardly.

    The border becomes red, raised and scaly, while the center clears and reveals fine scaling. 

    The rash can appear anywhere on the body: the arms, legs, face, etc. It may be itchy, but it typically isn't painful. Some ringworm infections, especially those treated with a steroid like hydrocortisone, develop vesicles or pustules in the advancing borders or in the centers.

    Diagnosis & Treatment of Ringworm

    Ringworm has a pretty unmistakable appearance and is therefore easy to diagnose, but in some cases, infections appear similar to other skin conditions such as granuloma annular, nummular eczema and tinea versicolor. If a doctor is unsure, a KOH test will be used to provide an accurate diagnosis. Fungal cultures are rarely used to identify the specific type of fungus responsible. 

    With proper treatment, ringworm usually resolves within 2 to 4 weeks. Doctors typically prescribe topic anti-fungal creams that are to be applied to lesions twice daily for at least 3 weeks. Although lesions usually clear up in about 2 weeks, treatment should continue for another full week to be sure the fungus is completely gone.

    Some topical creams can be purchased over the counter; others require a prescription.

    The most frequently used topical anti-fungal creams include:

    • Monistic (miconazole)
    • Mycelex (clotrimazole)
    • Nizoral (ketoconazole)
    • Lamisil (terbinafine)

    If an individual has multiple ringworm lesions, or if the lesions are extensive, an oral anti-fungal medication may be prescribed, which has a 100 percent clinical cure rate. Recommended oral antifungal medications include:

    • Terbinafine (Lamisil) 250 mg
    • Itraconazole (Sporanox) 200 mg

    How to Prevent Ringworm

    Fungi thrive in warm, moist conditions, the primary way to prevent ringworm is by staying clean and dry, as well as avoiding contact with contaminated objects and surfaces.


    Because fungi prefer warm, moist environments, preventing ringworm involves keeping skin dry and clean, and avoiding contact with infected material. To avoid future infection:

    • Maintain proper hygiene practices, especially if participating in sports that require close physical contact with others
    • Do not share personal items (combs, clothes, towels, etc.)
    • Wash your hands after handling animals, soil, and plants
    • Treat pets infected with ringworm
    • Do not touch characteristic lesions on others
    • Wear loose-fitting clothing
    • Keep damp areas where fungi thrive clean, i.e. bathtubs, bathroom floors, sinks, etc.


    Mims CA, Playfair JH, Roitt, IM, Wakelin D, Williams R, and Anderson RM. Medical Microbiology. ©1993. Mosby-Year Book Europe Limited. London, UK.

    Ringworm. MedlinePlus. US National Library of Medicine and the National Institutes of Health.