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Ecthyma is a skin infection similar to impetigo. It is often called deep impetigo because it occurs deep inside the skin.


Ecthyma is most often caused by the Streptococcus bacteria. Sometimes, Staphylococcus bacteria causes this skin infection.

The infection may start in skin that has been injured due to a scratch or insect bite. The infection often develops on the legs.


Main symptom of ecthyma is a small blister with a red border that may be filled with pus. The blister is similar to that seen with impetigo, but the infection spreads much deeper into the skin.

After the blister goes away, a crusty ulcer appears.

Exams and Tests

Your doctor can usually diagnose this condition simply by looking at your skin. In rare cases, the fluid inside the blister is sent to a lab for closer examination, or a skin biopsy needs to be done.


Your doctor will usually prescribe antibiotics that you need to take by mouth (oral antibiotics). Very early cases may be treated with  antibiotics that you apply to the affected area (topical antibiotics). Serious infections may need antibiotics given through a vein (intravenous antibiotics).

Placing a warm, wet cloth over the area can help remove ulcer crusts. Your doctor may recommend antiseptic soap or peroxide washes to speed recovery.

Outlook (Prognosis)

Unlike impetigo, ecthyma can sometimes result in scarring.

Possible Complications

  • Spread of infection to other parts of the body
  • Permanent skin damage with scarring

When to Contact a Medical Professional

Make an appointment with your health care provider if you have symptoms of ecthyma.


Carefully clean the skin after an injury such as a bite or scratch. Do not scratch or pick at scabs and sores.


Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. Philadelphia, Pa.: Elsevier Mosby; 2009:chap 9.

Pasternack MS, Swartz MN. Cellulitis, necrotizing fasciitis, and subcutaneous tissue infections. In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, Pa.: Elsevier Churchill-Livingstone; 2009:chap 90.

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Update Date 5/15/2013

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