What is ringworm?
Ringworm is a rash caused by a fungus in the skin. Ringworm is caused by various genera and species of fungi (for examples, Trichophyton species, Epidermophyton species). The term ringworm is used because the rash often occurs in a ringlike, circular pattern. Ringworm is also referred to as a form of tinea or dermatophytosis. Other terms for ringworm are based on the location of the infection, such as athlete's foot, jock itch (groin), and others. Ringworm is a common skin infection worldwide.
Is ringworm contagious?
Ringworm is very contagious. Ringworm can be transferred from person to person by direct contact (skin to skin) and also by indirect contact such as touching an infected person's clothing or even by touching a bench or other object that has contacted an infected person's skin. It can be acquired in swimming pool and hot tub areas by indirect contact. Humans can acquire ringworm from animals (for example, from dogs).
How long is ringworm contagious? Is ringworm contagious during treatment?
Ringworm is contagious as long as lesions are present. It stops being contagious about 24-48 hours after treatment begins.
What is the incubation period for ringworm?
The incubation period ranges from about four to 14 days.
How will I know if I am infected with ringworm?
The time from initial contact with the fungus to symptoms (incubation period) ranges from about four to 14 days and, depending upon what part of the body's infected, symptoms and signs can be itchy skin with a ring-shaped rash, red, scaly and cracking skin or plaques, and/or hair loss. It is possible for ringworm to be contagious during the incubation period (before ringworm symptoms and signs are apparent). If the fingernails become infected, the fingernails may become discolored and thickened. Patients with abnormally depressed immune systems usually have more severe symptoms and may develop skin abscesses and large areas of infected skin. Most ringworm infections are diagnosed by a microscopic examination of skin scrapings. Sometimes a fungal culture of the infected skin area is used to identify the infection. Some clinicians suggest that close relatives of infected individuals also be treated even if they show no symptoms or signs of ringworm since often family members of an infected person frequently become infected.
Often, the diagnosis of ringworm is obvious from its location and appearance. Otherwise, skin scrapings for microscopic examination and a culture of the affected skin can establish the diagnosis of ringworm. If the diagnosis is unclear, a potassium hydroxide (KOH) preparation of a skin scraping can be reviewed under the microscope to confirm the diagnosis of a fungus.
How does ringworm spread?
Ringworm is easily spread from person to person by touching infected areas on another person or by touching clothing or other objects that have been in contact with an infected person. Ringworm can be spread by people using locker rooms for swimming pools or locker rooms for other athletic events. People who have excessive sweating and wear tight clothing are more susceptible to ringworm infection. Ringworm infection is common in wrestlers. Covering skin areas that are infected with ringworm does not guarantee that a person is not contagious. Theoretically, direct skin-to-skin contact in water or a swimming pool or hot tub may spread the infection but is far less likely to do so than direct skin-to-skin contact elsewhere. In addition, it is possible to become infected from infected animals that have ringworm.
How will I know if I am cured of ringworm?
In general, ringworm is not contagious about 24-48 hours after topical medication treatment. However, treatment protocols usually require about one to two weeks of treatment. If treatment is interrupted or not completed, it is possible to have ringworm reoccur. Most forms of ringworm can be treated with over-the-counter medications in cream, lotion, or powder forms. These include clotrimazole (Lotrimin, Mycelex, and many others). These medications are antifungal medications. Even if an individual is successfully cured of ringworm, it is still possible to become reinfected if the individual encounters another source of infection (an infected person or contaminated object).
When should I seek medical care for a ringworm infection?
Many individuals can be treated with over-the-counter creams and lotions and cured. However, this treatment may not work for all individuals. Individuals should contact a health-care provider if they have a ringworm infection that is getting worse or does not resolve using over-the-counter medications. Ringworm on the scalp usually requires treatment with prescription antifungal medications, so these individuals should contact their physician for treatment. Individuals who have a weakened immune system must contact their physician quickly as severe infection with complications may occur, including secondary bacterial infections.
Medically Reviewed on 5/24/2018
Lesher, Jack L. "Tinea Corporis." Medscape.com. Feb. 22, 2018. <http://emedicine.medscape.com/article/1091473-overview>.
United States. Centers for Disease Control and Prevention. "Ringworm." Aug. 16, 2017. <http://www.cdc.gov/fungal/diseases/ringworm/>.