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Definition

Ringworm is a skin infection due to a fungus. Often, there are several patches of ringworm on the skin at once. The medical name for ringworm is tinea.

Alternative Names

Dermatophytid; Dermatophyte fungal infection - tinea; Tinea

Causes

Ringworm is common, especially among children. But, it can affect people of all ages. It is caused by a fungus, not a worm like the name suggests.

Many bacteria, fungi, and yeast live on your body. Some of these are useful, while others can cause infections. Ringworm occurs when a type of fungus grows and multiplies on your skin.

Ringworm can spread from one person to another. You can catch ringworm if you touch someone who has the infection, or if you come in contact with items contaminated by the fungus, such as combs, unwashed clothing, and shower or pool surfaces. You can also catch ringworm from pets. Cats are common carriers.

The fungus that causes ringworm thrives in warm, moist areas. Ringworm is more likely when you are often wet (such as from sweating) and from minor injuries to your skin, scalp, or nails.

Ringworm can affect the skin on your:

Gallery

Dermatitis - reaction to tinea
This picture shows a skin inflammation of the fingers with multiple blisters (vesicles) caused by an allergic reaction to a fungal infection (tinea corporis). (Image courtesy of the Centers for Disease Control and Prevention.)
Dermatitis - reaction to tinea
This picture shows a skin inflammation of the fingers with multiple blisters (vesicles) caused by an allergic reaction to a fungal infection (tinea corporis). (Image courtesy of the Centers for Disease Control and Prevention.)
Hair follicle
Each hair sits in a cavity in the skin called a follicle. Over time the follicle can shrink causing the hair to become shorter and finer. Ordinarily, the hair should grow back but in men who are balding the very small follicle ceases to grow any hair. The cause of baldness is not well understood, but is thought to be related to the genes and male sex hormones of the individual.
Dermatitis - reaction to tinea
This picture shows a skin inflammation of the fingers with multiple blisters (vesicles) caused by an allergic reaction to a fungal infection (tinea corporis). (Image courtesy of the Centers for Disease Control and Prevention.)
Psoriasis - magnified x4
This picture shows a 400% magnification of psoriasis. The whitish scales give the silvery appearance to the typical psoriasis lesion.
Dermatitis - reaction to tinea
This picture shows a skin inflammation of the fingers with multiple blisters (vesicles) caused by an allergic reaction to a fungal infection (tinea corporis). (Image courtesy of the Centers for Disease Control and Prevention.)
Tinea (ringworm)
Ringworm is a common skin disorder, especially among children, but may occur in people of all ages. It is caused by mold-like fungi (dermatophytes).

References

Elewski BE, Hughey LC, Hunt KM, Hay RJ. Fungal diseases. In: Bolognia JL, Schaffer JV, Cerroni L, eds. Dermatology. 4th ed. Philadelphia, PA: Elsevier; 2018:chap 77.

Hay RJ. Dermatophytosis (ringworm) and other superficial mycoses. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Disease. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 266.

Last reviewed April 14, 2021 by Elika Hoss, MD, Senior Associate Consultant, Mayo Clinic, Scottsdale, AZ. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team..

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