Impetigo is a contagious skin infection that usually affects children. It can develop if bacteria get into healthy skin or into minor cuts, scrapes, or any other small openings (such as those caused by bug bites). Other terms for impetigo are pyoderma and impetigo contagiosa.
Impetigo is usually caused by a bacterium called "Staphylococcus aureus," a type of "staph" infection. Less commonly the infection is caused by another bacterium called streptococcus group A, or "strep." (see "Patient information: Methicillin-resistant Staphylococcus aureus (MRSA) (Beyond the Basics)").
Impetigo is most common among children ages two to five years, but it can also affect older children and adults. The infection usually occurs in warm, humid conditions and is easily spread among people in close contact.
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Impetigo causes red bumps on the skin, usually on the face, arms, or legs. These bumps eventually form blisters that then burst and scab over with a distinctive yellow, gold, or brown crust (picture 1). In some cases, the blisters become painful sores that slowly heal (picture 2).
If you have impetigo, your doctor or nurse can usually diagnose the condition just by looking at the affected parts of your skin. In some cases, your doctor or nurse will take samples of pus from one of the blisters to confirm the presence of bacteria, but that is not usually necessary.
Depending on how severe and extensive your infection is, your doctor or nurse may recommend a topical cream or ointment or oral antibiotics.
If you have just a few affected spots that do not seem to penetrate deep into the skin, antibiotics in an ointment or cream may be all that is needed. On the other hand, if you have a larger infection, if the infection goes deep into the tissue, or if the areas are hard to reach, you may need antibiotics in pill form.
The antibiotic ointment experts recommend for impetigo is a prescription medicine, mupirocin (Bactroban®). You must apply this medicine to the infected parts of your skin. Be sure to finish the entire course of treatment to be sure that the infection does not come back.
If you get antibiotics in pill form, you will probably have to take them for seven days or longer. Take all the antibiotics prescribed to you, even if your skin clears up before you complete the medicine.
Impetigo is typically spread from person to person through direct skin-to-skin contact. To keep from getting impetigo, the most important thing you can do is wash your hands with soap and water right after you touch anyone who has the infection. If you are not near a sink, an alcohol-based hand-rub will work, too.
To prevent the spread of impetigo and of other infections, take the following precautions:
- Wash your hands with soap and water often (no matter whom you touch) and use alcohol hand rubs. Do not share personal items, such as towels, clothes, or hair combs. The germs that cause impetigo can live on these objects.
- Wash towels and bed linens in hot water and dry them on high heat.
- If you have impetigo, try covering the parts of your skin that are infected. Otherwise, if you scratch the affected skin and then touch yourself elsewhere, you can spread the infection to other parts of your body. Plus, the bacteria will get on your hands and anything you touch.
- Always use disposable tissue paper to blow your nose and teach your children to do the same. If you have impetigo on your nose or face, the germs that cause impetigo will wind up on the tissue. Also, wash your hands after handling tissues that could be carrying germs.
- When you sneeze, sneeze into the crook of your arm or into your shoulder, not into your hands. Otherwise the bacteria from your nose and mouth will end up on your hands and anything you touch.
If you get impetigo over and over again, see a dermatologist (a doctor who specializes in treating skin disorders). You might have another skin problem that is making it hard for your body to fight the infection.
WHERE TO GET MORE INFORMATION
Your healthcare provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient information: Impetigo (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient information: Methicillin-resistant Staphylococcus aureus (MRSA) (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
The following organizations also provide reliable health information.
- National Library of Medicine
- National Institute of Allergy and Infectious Diseases