What Is Impetigo?

Group A streptococcus bacteria
National Institute of Allergy and Infectious Diseases (NIAID)/CC BY 2.0
In This Article

Impetigo is a highly contagious bacterial skin infection that causes sores and a honey-colored crust or blister-like bumps. It can be itchy and painful, and it occurs when skin—especially already irritated or broken skin—comes in contact with a common type of staph or the bacteria responsible for strep throat.

Impetigo can happen to anyone, but it typically affects infants and children and is most common in those ages 2 to 5. Those diagnosed with impetigo are usually treated with topical antibiotics or oral antibiotics to avoid complications and prevent its spread.

Types of Impetigo

There are three types of impetigo that are classified based on the appearance of the infected skin and how deep the infection goes into skin layers:

  • Nonbullous impetigo (impetigo contagiosa): The most common form of impetigo, it involves only the outermost layers of skin called the epidermis and begins as red, itchy sores that drain clear fluid or pus for a few days. Honey-colored, crusted lesions then develop over the sores.
  • Bullous impetigo: This type also affects the epidermis and causes much larger skin lesions that look like blisters and may stay intact on the skin longer before rupturing.
  • Ecthyma (deep impetigo): This is a more serious bacterial infection that goes into the deeper skin layer of the dermis. It begins as a pustule and leads to ulcerative sores.

Impetigo Symptoms

Nonbullous impetigo often occurs in areas where the skin has been broken, irritated, or damaged. The nostrils, especially in kids with runny noses, are commonly affected. The face, the neck, and the hands are other areas of the body where you are likely to see lesions. 

Untreated infections can quickly spread to other areas on the child's body. Itchiness may occur, but scratching can further spread the infection.

This photo contains content that some people may find graphic or disturbing.

Impetigo on a child's arm
Impetigo on a child's arm. Matthew Roberge / Getty Images

Nonbullous impetigo tends to form in areas where skin folds or rubs against other skin. This type commonly affects a child's trunk or buttocks. It can also form in areas such as the armpits or groin.

If you notice any itchy or painful red bumps, a honey-colored crust over sores, or blister-looking bumps in your child's skin folds, call the pediatrician immediately so that it can be treated and to prevent if from spreading to other parts of the child's body and to other people.

Causes

Impetigo can occur when skin is exposed to either:

  • Staphylococcus aureus, a type of staph responsible for a variety of types of skin infections and other concerns
  • Group A Streptococcus (GAS or Group A strep, also known as Streptococcus pyogenes), also responsible for strep throat, cellulitis, and other infections

The likely culprit(s) of a case of impetigo ultimately depends on the type that occurs.

Impetigo Type Caused by S. aureus Caused by Group A strep
Nonbullous
Bullous  
Ecthyma

Ecthyma can occur from untreated impetigo that develops into a deeper infection.

Impetigo can develop as a primary infection when the bacteria infects normal skin, or it can form as a secondary infection when bacteria invades already irritated or open skin, such as from a wound, insect bite, poison ivy, eczema, herpes, or scabies.

Direct contact with infected lesions is what causes spread. This can occur in a number of ways and settings, such as:

  • When a child scratches an infected area and then touches another part of their body
  • Hugs, hand-shaking, or other forms of direct contact with an infected individual
  • Engaging in certain sports, such as wrestling
  • Crowded areas, such as schools or daycare centers

The S. aureus bacteria commonly colonize (live on) the skin of children and adults. It is especially common to find it in the nose, so it can be passed easily if children pick their noses.

Though technically one step removed from direct contact, the infection can also spread if you touch the clothes, towels, or sheets of an infected person.

The bacteria that lead to impetigo thrive in hot and humid environments and infections are more common in tropical or subtropical climates.

Diagnosis

Diagnosis of impetigo is usually made after a doctor examines the skin and notices the typical appearance of the infection.

A doctor may also want to do a bacterial culture if they suspect that impetigo is being caused by a resistant bacteria, such as MRSA (methicillin-resistant staphylococcus aureus), or if a rash is not going away.

Treatment

For small areas of infection, an over-the-counter or prescription-strength topical antibiotic is typically all that is needed. You will also need to regularly wash the area with warm, soapy water and then cover it with a bandage to prevent spread to others.

For more extensive or persistent infections, an oral or intravenous antibiotic might be needed. Ecthyma is typically treated with oral antibiotics, for example.

MRSA is resistant to many of the antibiotics that are commonly used to treat impetigo, including Keflex (cephalexin), Augmentin (amoxicillin, clavulanic acid), Zithromax (azithromycin), and cefdinir. If MRSA is the cause of the infection, a stronger antibiotic, such as Cleocin (clindamycin) or Bactrim (sulfamethoxazole, trimethoprim), may be needed.

Once treatment starts, the infection should begin to disappear within a few days. If you aren't noticing a change, let your physician know since a different medication may be needed.

Repeat Infections

It is possible to get impetigo more than once. If impetigo or other staph-related skin infections continue to occur, your doctor may recommend that all members of your household get treated with antibiotics, such as Bactroban (mupirocin) nasal gel twice a day for five to seven days.

Other measures, such as baths with Hibiclens (an antiseptic, antimicrobial skin cleanser) and very frequent hand washing, may also be recommended.

How Long Is Impetigo Contagious?

Children are usually no longer contagious once they have been on antibiotics for 24 to 48 hours, there is no longer a discharge, and you are seeing signs of improvement.

Prognosis

Most cases of impetigo resolve without complications or scarring. If a scar does occur, it is typically from a deep infection of ecthyma. In these cases, you may want to see a dermatologist who can offer treatments to minimize the appearance of the scar.

In extremely rare cases, impetigo can lead to serious complications if it goes untreated. This can include:

  • Post-streptococcal glomerulonephritis, inflammation of the filters of the kidneys that can develop after a Group A strep infection. This can lead to hematuria (bloody urine) and high blood pressure.
  • Scarlet fever, a condition caused by Group A strep that is characterized by fever, rash, and a red tongue
  • Septicemia, a serious blood infection caused by bacteria

If you child has a fever, blood in their urine, or is lethargic, seek urgent medical attention.

A Word From Verywell

As with most infections, one of the best preventative steps you can take to reduce your risk of impetigo or prevent an existing infection from spreading is to wash your hands frequently and for at least 20 seconds each time. Make sure children follow good hand hygiene, and if they have any bites, scrapes, or rashes, keep a close eye on them and keep them clean and covered.

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Article Sources
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  1. Centers for Disease Control and Prevention. Impetigo. Updated May 29, 2020.

  2. Hartman-adams H, Banvard C, Juckett G. Impetigo: diagnosis and treatment. Am Fam Physician. 2014;90(4):229-35.

  3. Peppard WJ, Daniels A, Fehrenbacher L, Winner J. Evidence based approach to the treatment of community-associated methicillin-resistant Staphylococcus aureusInfect Drug Resist. 2009;2:27–40. doi:10.2147/idr.s3794

  4. Creech CB, Al-Zubeidi DN, Fritz SA. Prevention of Recurrent Staphylococcal Skin InfectionsInfect Dis Clin North Am. 2015;29(3):429–464. doi:10.1016/j.idc.2015.05.007

  5. American Academy of Dermatology Association. Impetigo: diagnosis and treatment.

  6. National Institute of Diabetes and Digestive and Kidney Diseases. Glomerular diseases. Updated April 2014.