Taking the history

Diagnosis is usually based on the clinical appearance and history.

Ask about:
• The appearance, onset, evolution, duration and location of lesions
• Contact with others with impetigo (e.g. at school, play group or gym)
• Recent or pre-existing skin conditions (e.g. eczema, insect bites, abrasions, scabies, chickenpox, herpes simplex)
• Immunosuppression (e.g. resulting from pre-existing disease or immunosuppressive treatment)
• Previous episodes (recurrent impetigo is defined as two or more episodes in one year)
• Previous topical or oral treatment for this episode of impetigo 
• Presence of fever.

Examining the patient

A visual examination should be sufficient to determine the nature and extent of the skin lesions. The purpose of the examination is to: 

• Look for the clinical features of impetigo
• Determine whether the lesions are those of localised or widespread, non-bullous impetigo. (Localised disease – three or fewer lesions or clusters present; widespread disease – four or more lesions or clusters present)
• Check for features of systemic involvement (e.g. fever, lethargy, feeling unwell)
• Exclude bullous impetigo, recurrent impetigo and other skin conditions that could look similar.