ByWingfield E. Rehmus, MD, MPH, University of British Columbia
Reviewed/Revised Jun 2023

Erythrasma is infection of the top layers of the skin caused by the bacterium Corynebacterium minutissimum.

(See also Overview of Bacterial Skin Infections.)

Erythrasma affects mostly adults, especially those with diabetes and those living in hot and humid climates.

Erythrasma is most common in the foot, where it causes scaling, cracking, and breakdown of the skin between the last two toes. This infection is also common in the groin, where it causes irregularly shaped pink or brown patches and fine scaling especially where the thighs touch the scrotum (in men). The armpits, skinfolds under the breasts or on the abdomen, and the area just in front of the anus (perineum) are prone to this infection, particularly among people with diabetes and among middle-aged women with obesity.

In some people, the infection spreads to the torso and anal area.

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This photo shows characteristic pink-brown patches of erythrasma in and surrounding the skinfolds of the groin.
Image provided by Thomas Habif, MD.

Diagnosis of Erythrasma

  • A doctor's evaluation

Although erythrasma may be confused with a fungal infection, doctors can easily diagnose erythrasma because skin infected with Corynebacterium glows coral-red under an ultraviolet light.

Treatment of Erythrasma

  • Antibiotics taken by mouth or applied to the skin

Erythrasma may return, necessitating a second round of treatment.

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