Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at June 27, 2016

Impetigo is a common skin infection. Although the condition can occur in adults, it is most often seen in young children and infants. Impetigo is extremely contagious and can be easily spread through close contact and by sharing clothing, towels, sheets, toys, and other items.


Definition & Facts

There are several different types of impetigo with each having slightly different causes and symptoms. Impetigo contagiosa is the most common type of impetigo and typically starts with red, blistering sores around the mouth and nose.

Bullous impetigo is most common in children under the age of two who still wear diapers. This form of impetigo is characterized by clear or cloudy blisters on the trunk, buttocks, arms, and legs. The most serious form of impetigo is called ecthyma. In this type of impetigo, the infection extends to the second layer of skin

Symptoms & Complaints

The classic symptoms of impetigo contagiosa include small, red papules that may resemble a pimple. These papules develop into blisters, which break open and ooze fluid. The sores then develop a yellowish or honey-colored crust. The sores, which may be itchy, can increase in number and may be as large as a coin.

In addition to skin lesions, a child with impetigo may also have tender or swollen lymph nodes near the affected area. The skin lesions typically heal within one to three weeks with proper treatment.

The bullous form of impetigo normally features larger blisters. The blisters are caused by a toxin produced by the bacteria that causes the top layer of skin to separate from the lower layer. These blisters are filled with a clear or yellowish fluid. The blisters break easily, leaving an area of raw skin with a ragged edge.

The ecthyma form of impetigo features deep, pus-filled sores that can develop into painful ulcers and open sores that can take much longer to heal. In rare instances, the bacterial infection causing impetigo may spread to the bloodstream and lymph nodes, which can lead to cellulitis. It is also possible for the bacteria to damage the kidneys


Impetigo is caused by either streptococcus or staphylococcus bacteria. The incubation period for streptococcus infections ranges from one to three days. The incubation period for staphylococcus infections is slightly longer at four to 10 days. The bacteria enter the body at an area where skin integrity has been compromised by irritation or injury.

Children frequently develop impetigo after experiencing a common cold or allergies since the skin under the nose is often raw. Other skin problems, including burns, cuts, insect bites, poison ivy, and eczema can provide a pathway for the bacteria to enter the body. Risk factors for developing impetigo include:

  • Being under the age of six.
  • Attending school or daycare.
  • Living in a warm, humid climate.
  • Having poor hygiene habits. 
  • Being in a crowded environment where germs can spread easily.
  • Having other skin conditions or broken skin.
  • Participating in sports or other activities with frequent skin-to-skin contact, such as wrestling or football.
  • Having diabetes.
  • Having a weakened immune system

Diagnosis & Tests

In most cases, a doctor will diagnose impetigo through physical examination by looking for the characteristic skin lesions with the honey-colored crust. The doctor may wish to perform a culture and antibiotic sensitivity test to identify the specific bacteria causing the infection and to determine which antibiotics will prove most effective in treating the condition. This involves brushing the affected area with a swab or removing a small piece of the lesion to be sent to a lab for analysis. The doctor may also order blood tests or clinical urine tests if the child has other signs of illness that may indicate a systemic infection. 

Treatment & Therapy

Most mild cases of impetigo are easily treated with topical antibiotics, including mupirocin. In the case of topical antibiotic creams, it may be necessary to use wet compresses or to soak the affected area to remove the scabs before applying the cream. This will allow the antibiotic to penetrate through to the skin. Oral antibiotics are usually used when the lesions are more widespread. The oral antibiotics most frequently used to treat impetigo include amoxicillin clavulanate and cephalexin.

If the bacterial culture shows methicillin-resistant Staphylococcus aureus, the doctor may prescribe stronger antibiotics, including clindamycin or trimethoprim-sulfamethoxazole. It is important to complete the entire course of antibiotics as prescribed to ensure that all of the bacteria are destroyed and to prevent antibiotic resistance.

A child is usually allowed to return to school or daycare after being on antibiotic treatment for 24 to 48 hours. Parents should keep their keep their child’s fingernails trimmed short to prevent scratching, which can spread the infection. Parents should also follow up with their child’s doctor if the infection appears to worsen or if the child develops a fever or redness, warmth, swelling, or increased pain in the affected area. 

Prevention & Prophylaxis

The best way to prevent impetigo is to follow basic rules of proper hygiene. This includes washing the hands regularly, showering or bathing daily, and keeping any skin injuries clean and covered. Try to avoid close contact with individuals known to have impetigo until the lesions have cleared.

People with impetigo should not share personal hygiene items with family members. The infected person’s clothing, towels, and bedding should be washed daily, preferably in hot water.

Parents treating their children should wear gloves when applying antibiotic ointments or coming into contact with lesions. Afterwards, the hands should be washed thoroughly with antibiotic soap. Lesions can also be covered lightly with gauze to reduce the risk of scratching or infecting others.

Household surfaces that the infected individual may touch, such as doorknobs, faucets, counters, and toys, should be disinfected frequently with antibacterial wipes or cleaners. Children should be kept out of school or daycare until a doctor advises they are no longer contagious.

Most cases of impetigo resolve without complication with antibiotic therapy. The skin lesions caused by impetigo are primarily superficial and normally heal without scarring. Any residual redness at the affected area should fade in a few days to weeks. 

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