Is Ringworm Contagious?

  • Medical Author:
    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Ringworm Diagnosis

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.

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.

Medically Reviewed by a Doctor on 9/21/2016

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