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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 cause 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

This condition may lead to:

  • 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.


Millett CR, Halpern AV, Reboli AC, Heymann WR. Bacterial diseases. In: Bolognia JL, Jorizzo JL, Schaffer JV, eds. Dermatology. 3rd ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 74.

Pasternack MS, Swartz MN. Cellulitis, necrotizing fasciitis, and subcutaneous tissue infections. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 95.

Version Info

  • Last reviewed on 4/20/2015
  • Chad Haldeman-Englert, MD, FACMG, Wake Forest School of Medicine, Department of Pediatrics, Section on Medical Genetics, Winston-Salem, NC. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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