 - An allergic anaphylactic reaction is characterized by an adverse local or general response from exposure to an allergen involving skinmucosal tissue manifestations hives, pruritus, flushing, angioedema, andor respiratory compromise dyspnea, wheeze-bronchospasm, stridor, reduced peak expiratory flow, hypoxemia, andor hemodynamic effects hypohypertension, hypotonia, syncope. 