Impetigo

What is impetigo?

Impetigo is a contagious bacterial infection of the surface of the skin. In the UK it is the commonest skin infection in children, though adults can get it too.

Who gets it?

Impetigo can affect anybody, but it is more likely with diabetes, weakened immunity, or skin that is already broken, for example by cuts, grazes, bites, cold sores, eczema or psoriasis. It spreads easily within families, schools and other close communities, and is more common in warm, humid weather.

What causes it?

Impetigo is caused by bacteria called Staphylococcus aureus or Streptococcus. These bacteria often live harmlessly on the skin or in the nose and can cause infection when they get into broken or damaged skin.

Is it hereditary or contagious?

Impetigo is not inherited, although it often spreads between family members. It is contagious and spreads through direct skin contact or through shared towels, bedding and clothing. It can also spread to other areas of your own skin through scratching or touching the sores.

What does it look and feel like?

Impetigo usually starts as small, fluid-filled blisters that quickly burst, leaving red or darker sores covered with yellow, golden or brownish crusts. Patches are generally under 1 cm across at first but may slowly spread. They can be itchy or mildly sore. The most common sites are around the nose and mouth and on the hands, but impetigo can occur anywhere.

Types of impetigo

Non-bullous impetigo is the most common type and causes the typical golden crusts.

Bullous impetigo causes larger, loose, fluid-filled blisters that burst and leave a thin crust. People with eczema or psoriasis are more prone to it.

Ecthyma is a rare, deeper form of infection that causes painful ulcers with thick crusts, which can heal with scarring.

How is it diagnosed?

Impetigo is usually diagnosed from its appearance. A swab may be taken to identify the bacteria, particularly if the infection keeps coming back or does not settle. If impetigo keeps recurring, your doctor may check whether you carry the bacteria in your nose, or look for an underlying skin condition such as eczema.

What is the outlook?

Impetigo clears quickly with the right management and usually heals without scarring, although the skin can be left temporarily lighter or darker, particularly on brown and black skin.

More information

British Association of Dermatologists patient leaflet: https://www.bad.org.uk/pils/impetigo

This page gives general information only and is not a substitute for a consultation. Everyone's skin is different, and what is right for you will depend on your own circumstances. If you are worried about a skin problem, please book an appointment with Dr Mounsey or speak to your GP. If you have a mole or skin lesion that is changing, bleeding or growing quickly, please seek medical advice promptly.