Acute urticaria is a common disorder. It can be either allergic (a reaction between an antigen and specific mast cell-bound IgE) or nonal - lergic. Recognized precipitants include drugs (commonly aspirin, NSAIDs, antibiotics, opiates), foods (e.g. shellfish, nuts, food dyes), and infections (Epstein-Barr virus, hepatitis B, Streptococcus). Contact urticaria occurs when an allergen is absorbed across skin or mucous membranes producing a localized or systemic reaction (e.g. latex allergy). However, in many cases a specific trigger is not identified. Acute urticaria usually presents as a widespread, extremely itchy eruption often with a sudden onset.