Impetigo Explained: Symptoms, Causes, and How to Treat It

Medically Reviewed By Karen Gill, M.D.
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Impetigo is a common and infectious bacterial infection of the skin. It is most common in young children between 2 and 5 years old. However, adults can also develop impetigo. Impetigo occurs due to infection by the Staphylococcus aureus or Streptococcus pyogenes bacteria. These bacteria are naturally present on your skin. However, sometimes they can enter the upper layers of your skin through a cut, scratch, or rash. In some cases,

you can still develop impetigo even if you don’t have a visible break in your skin.

Impetigo can develop anywhere on the body. However, you are more likely to develop impetigo on exposed areas such as your nose, mouth, arms, and legs.

Talk with your medical professional if you have an itchy rash with blisters, blisters that leak a yellowish fluid or pus, red skin around the blisters, or swelling. If you experience difficulty breathing, loss of consciousness, or high fever, seek immediate medical care (call 911).

This article discusses the types of impetigo and its symptoms, causes, and risk factors. It also gives guidance on when to contact a doctor, treatment options, and possible complications.

What are the different types of impetigo?

Young girl at doctor with pediatrician applying bandage to upper arm
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If you have impetigo, you will develop a rash that lasts a few days. The blisters in the rash break open and leak a yellowish fluid or pus. As the blisters heal, crusty yellow scabs form over the red sores.

Impetigo spreads through contact with the rash, sores, or mucus of someone who has the infection. You can also spread impetigo by sharing items such as towels or clothing with an infected person.

There are two types of impetigo: nonbullous and bullous. Another, more serious, infection similar to impetigo is ecthyma.

Nonbullous impetigo

About 70% of impetigo cases are nonbullous. This common type of impetigo results from both Staphylococcus aureus and Streptococcus pyogenes bacteria.

A few days after the infection sets in, you will notice small, itchy blisters that soon burst open and leak a yellowish liquid. The surrounding skin is red or discolored. The raw sores then form yellow or honey-colored crusts. You may feel that your lymph glands in the area are swollen and tender. The skin usually heals without scarring.

Bullous impetigo

About 30% of impetigo cases are bullous. This type of impetigo is due to Staphylococcus aureus bacteria.

You will see blisters larger than those that form with nonbullous impetigo. They may contain cloudy or yellow fluid. The blisters become limp and transparent before they break open. The surrounding skin does not appear red or discolored. The sores then form yellowish crusts. As in nonbullous impetigo, the skin usually heals without scarring.

Ecthyma

This is a much less common type of impetigo. In rare cases, ecthyma can develop when impetigo does not receive prompt treatment. It is a more serious type of infection because the infection penetrates deeper into the skin.

You will notice painful blisters that turn into deep sores with thick crusts. The surrounding skin is often red or discolored. This infection often leads to scarring.

What are the symptoms of impetigo?

About 162 million children worldwide have impetigo at any one time. Infants and young children often develop impetigo in the diaper area first. Older children and adults develop symptoms in exposed areas such as the nose, mouth, arms, and legs.

Common symptoms of nonbullous impetigo

  • an itchy rash that spreads 
  • small blisters that quickly burst and leak yellowish fluid
  • redness or discoloration of the surrounding skin
  • yellowish crusts that form over the sores
  • swollen lymph nodes near the infected area
  • blisters that heal without scarring

Common symptoms of bullous impetigo

  • larger blisters filled with cloudy liquid
  • blisters that first become limp and transparent, then burst open
  • yellowish crusts that form over the sores
  • blisters that heal without scarring

Symptoms of ecthyma

  • painful blisters that sometimes contain pus
  • blisters that turn into deep, raw sores
  • thick brown crusts that form over the raw sores
  • surrounding skin that is red-purple and may be swollen

Impetigo is usually a mild condition. In some rare cases, adults can develop complications that can be life threatening. These include kidney infection (post-streptococcal glomerulonephritis), cellulitis, and sepsis.

Seek immediate medical care (call 911) if you have any of the following symptoms:

  • confusion or loss of consciousness
  • difficulty breathing or rapid breathing
  • high fever (higher than 101°F)

What causes impetigo?

Impetigo is an infection from Staphylococcus aureus bacteria and Streptococcus pyogenes bacteria. Sometimes, these bacteria enter your body through a cut, scratch, insect bite, or rash. They then multiply and cause an infection. Impetigo can also develop on healthy skin.

Bacteria thrive in hot, moist conditions. In northern climates, weather conditions are ideal for bacteria during the summer and fall. In warm and humid climates, impetigo can occur throughout the year. It is more common in developing countries and in areas of low socioeconomic status. 

Impetigo is very contagious. It easily spreads if you touch the sores or the liquid that oozes from them. You can also catch the bacteria by coming into contact with the clothing or towels used by a person with impetigo. To prevent spreading the infection, always wash your hands after touching the infected areas. Also launder the clothing or the towels that a person with impetigo has used.

What are the risk factors for impetigo?

The bacteria that cause impetigo live all around us. Most people will not develop impetigo if these bacteria enter their bodies. The following factors can put children and adults are at higher risk for developing impetigo:

Is impetigo contagious?

Impetigo is highly contagious. A person with impetigo can spread the infection by touching the sores and then touching another part of their body, another person, or other objects.

People with impetigo should remain at home until they are no longer infectious. Impetigo is contagious until:

  • The rash disappears.
  • The scabs have fallen off.
  • You have finished at least 2 days of antibiotics.

The Centers for Disease Control and Prevention (CDC) advises that children may return to school or adults may return to work once they begin antibiotic treatment as long as they keep the sores covered.

How can I reduce my risk for impetigo?

Regular handwashing, maintaining clean living conditions, and washing and dressing cuts can reduce your risk for developing impetigo.

Here is a list of simple habits that can help you reduce your risk of spreading impetigo:

  • Wash your hands after touching or dressing the sores.
  • Launder the clothes, bedding, and towels that you have used.
  • Disinfect surfaces, toys, and dishes that you have used.
  • Avoid scratching the sores.

How doctors diagnose impetigo

In most cases, your doctor will be able to diagnose impetigo by looking at the infected area. Here is a list of questions the doctor may ask you:

  • When did you first notice the sores or blisters?
  • Did you notice a cut, scrape, or bite before the sores started?
  • Is the area painful or itchy?
  • What, if anything, seems to make the sores better or worse?
  • Have you been around anyone with a similar rash or sores?
  • What other medical conditions do you have?

If the treatment does not work, your doctor will take a culture by removing a little bit of the fluid. A laboratory test will help to identify the type of bacteria that is causing the infection. Your doctor will then be able to prescribe a suitable antibiotic treatment.

Treatment for impetigo

Because impetigo is a bacterial infection, doctors treat it with antibiotics.

Treatment for mild cases

For mild cases, your doctor will likely prescribe mupirocin cream or ointment (Bactroban or Centany) or retapamulin ointment (Altabax). Follow these steps 2–3 times a day for up to 10 days for best results:

  • Soak the skin or apply a wet compress.
  • Pat the area dry and gently remove crusts.
  • Apply the antibiotic to the sores.
  • Cover the sores with a nonstick bandage.

Treatment for widespread cases

If your impetigo is severe or widespread, your doctor can prescribe oral antibiotics such as a combination of amoxicillin and clavulanate (this combination goes by the brand name Augmentin).

What are the potential complications of impetigo?

Complications of impetigo are rare. In rare cases, impetigo can develop into ecthyma, most often in people with weakened immune systems or other risk factors. This is a more serious type of impetigo because the infection penetrates deeper into the skin.

More rarely, impetigo can lead to inflammation of structures in the kidney. This complication is called post-streptococcal glomerulonephritis. If someone has this complication, it usually starts 1–2 weeks after the skin sores heal.

Summary

Impetigo is a common and infectious bacterial infection of the skin. It usually happens when bacteria penetrate the upper layers of skin through a cut, insect bite, or rash.

Symptoms include an itchy rash with blisters that ooze and then crust over. Doctors treat mild cases of impetigo with antibiotic creams. More widespread cases may require oral antibiotics. Complications are rare.

If you suspect that you have impetigo, speak with your doctor to receive an accurate diagnosis and begin prompt, effective treatment.

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Medical Reviewer: Karen Gill, M.D.
Last Review Date: 2022 Mar 2
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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  2. Impetigo: All you need to know. (2021). https://www.cdc.gov/groupastrep/diseases-public/impetigo.html
  3. Johnson, M. K. (2020). Impetigo [Abstract]. https://pubmed.ncbi.nlm.nih.gov/33105179/