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Impetigo is a bacterial infection that involves the superficial skin. The most common presentation is yellowish crusts on the face, arms, or legs. Less commonly there may be large blisters which affect the groin or armpits. The lesions may be painful or itchy. Fever is uncommon.

Signs and Symptoms:

Contagious impetigo

It is also called nonbullous impetigo and is the most common form of impetigo. It often begins as a red sore near the nose or mouth which soon breaks, leaking pus or fluid, and forms a honey-colored scab, followed by a red mark which heals without leaving a scar. Touching or scratching the sores may spread the infection to other body parts and may also result in skin ulcers with redness and scarring. Sores can be itchy but are rarely painful. Swollen lymph nodes occur in the affected areas.

Bullous impetigo

It is mainly seen in children younger than 2 years, involves painless, fluid-filled blisters, mostly on the arms, legs, and trunk, surrounded by red and itchy (but not sore) skin. The blisters may be large or small. After they break, they form yellow scabs.


It produces painful fluid- or pus-filled sores with redness of skin. Ecthyma is the nonbullous form of impetigo which is usually on the arms and legs and becomes ulcers that penetrate the dermis. Hard, thick, gray-yellow scabs are formed when they break and sometimes leaves scars. Ecthyma can also result in swollen lymph nodes in the affected area.


It is typically due to either Staphylococcus aureus or Streptococcus pyogenes. Risk factors include attending day care, crowding, poor nutrition, diabetes mellitus, contact sports, and breaks in the skin such as from mosquito bites, eczema, scabies, or herpes. With contact it can spread around or between people.


Impetigo affected about 140 million people (2% of the world population) in 2010. It can occur at any age, but is most common in young children. In some places the condition is also known as "school sores". 


Without treatment people typically get better within three weeks. Complications may include cellulitis or poststreptococcal glomerulonephritis.

Top UK Dermatologists Online Consultation

For more information on this topic please click on the links below

Link to British Association of Dermatologists article on dermatology from DermUK
Link to DermNet NZ article on dermatology from DermUK
Link to Medscape dermatology article from DermUK
Link to NICE clinical knowledge summary on dermatology from DermUK

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Ichthyosis is a family of genetic skin disorders characterized by dry, thickened, scaly skin.


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