Often Confused With Jock Itch

Erythrasma is a bacterial infection caused by the bacteria Corynebacterium minutissimum. It occurs most often between the third and fourth toes, but it can also frequently be found in the groin, armpits, and under the breasts. Because of its color and location, it's often confused with a fungal infection like jock itch. Erythrasma is more common in the following populations:

  • Overweight people
  • Elderly
  • Diabetics
  • People in warm, moist climates

Erythrasma Appearance

Erythrasma starts as a pink to red patch with well-defined edges. This patch has a finely wrinkled appearance with a very fine scale on it. After some time, the rash fades from pink to a uniform brown color. This consistent brown color with the fine scale distinguishes it from jock itch or other fungal infections which are typically more red around the edges with thicker scaling on the edges.

Other Rashes Like Erythrasma

Even though erythrasma is often confused with jock itch, other skin conditions can look similar, including:

Erythrasma Diagnosis

At times, your doctor can diagnose erythrasma based on its typical appearance. But more often, your doctor will need to perform other tests to help make the diagnosis. The best way for your doctor to tell the difference between erythrasma and a fungal infection is to do a Wood's Lamp examination on the rash.

Under the UV light of a Woods Lamp, erythrasma turns a bright coral red, but fungal infections do not. Other tests that may help include:

  • Gram Stain: A way to identify bacteria from a sample of the scale. Unfortunately, this bacteria is difficult to get to stick to the slide so it requires a special technique.
  • KOH Test: This is a test used to identify fungal elements. This test might be done to confirm that there is no fungus present.
  • : A sample of tissue is removed and evaluated under a microscope. In erythrasma, the bacteria can be seen in the upper layer of the specimen.

Erythrasma Treatment

Since this is a bacterial infection, erythrasma is best treated with antibiotics, and fortunately, several antibiotics fit the bill. The following are antibiotics that are typically prescribed for erythrasma:

  • Erythromycin 250mg four times a day for 5 days
  • Clarithromycin 1gm once
  • The antifungal creams miconazole, clotrimazole, and econazole, but not ketoconazole
  • Topical antibiotics like clindamycin or erythromycin twice a day for 2 weeks


Blaise, G et al. "Corynebacterium-associated skin infections." International Journal of Dermatology. 47(2008): 884-90.

Habif, Thomas. "Bacterial Infections." Clinical Dermatology, 4th Edition. Ed. Thomas Habif, MD. New York: Mosby, 2004. 236-62.

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