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Impetigo - Bullous and Nonbullous Impetigo, and Ecthyma

Last Updated: Mar 1, 2019


Impetigo is a skin infection caused by bacteria, resulting in a red rash, blisters, and a characteristic honey-colored crust on the skin. Impetigo most commonly occurs in infants and children age 2 to 6.

There are three forms of impetigo:

  1. Nonbullous impetigo is the most common and mildest form of impetigo, causing small blisters on the skin.
  2. Bullous impetigo produces much larger blisters.
  3. Ecthyma is the most serious form of impetigo, affecting deeper levels of skin (dermis layer).


Impetigo is usually caused by Staphylococcus aureus or Streptococcus pyogenes bacteria. This highly contagious infection is spread from one person to the next by direct contact with the lesions or secretions of an infected person. The condition occurs on areas of skin where a person has a pre-existing scratch, cut or break in the skin through which the bacteria can enter.

impetigo on neck

Risk factors include:


Typically an individual with impetigo experiences the onset of symptoms within 1 to 3 days after acquiring the infection. The initial symptom of impetigo is a red rash, usually located on the face, arms or legs.


Severe forms of impetigo may lead to the following major complications:

Diagnosis and Treatment

Impetigo is usually diagnosed by visually observing the characteristic skin rash with honey-colored crust, so, in most cases, there is no need for additional testing. Sometimes, the fluid from weeping areas is tested in a laboratory to confirm the diagnosis and identify the bacteria involved.

Left untreated, the infection normally resolves itself in approximately 3 weeks. However, treatment with medication clears the infection much faster.

Treatment includes the following:


Impetigo is highly contagious and easily transmitted to others through contact with infected skin, shared objects, clothing and linens. The best way to prevent impetigo is to avoid contact with infected people and contaminated objects. Hand washing is considered vital in reducing the spread of infections. Additionally, the infection is only acquired when there is a break or cut on the skin, so children should be taught to avoid scratching, and their fingernails should be kept properly trimmed. After 48 hours of antibiotic treatment, a person with impetigo is no longer contagious.


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Tina Shahian, PhD

Tina is a writer for Innerbody Research, where she has written a large body of informative guides about health conditions.


A communication specialist in life science and biotech subjects, Tina’s successful career is rooted in her ability to convey complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. Tina Shahian’s Linkedin profile.


In her spare time, Tina enjoys drawing science-related cartoons.