Broadly, the blistering disorders include those diseases in which blister (bulla or vesicle) formation can occur as a skin reaction to infective agents or drugs (erythema multiforme, toxic epidermal necrolysis), the immunobullous diseases (pemphigus, bullous pemphigoid, pemphigoid/herpes gestationis, dermatitis herpetiformis), and the mechanobullous diseases (epidermolysis bullosa), of which there are various types. Acquired epidermolysis bullosa, however, is an immunobullous disease. In children, the commonest causes of blistering are insect bite reactions and bullous impetigo.