Idiopathic cold urticaria and anaphylaxis.

Cold urticaria (CU) is a subtype of physical urticaria characterized by the development of urticaria and angioedema after cold exposure. Symptoms typically occur minutes after skin exposure to cold air, liquids, and objects. Most common method to confirm the diagnosis of CU is through ice cube challenge test, but 20% of patients with CU have negative ice cube challenge test results. The greatest risk with this kind of urticaria is the development of systemic reaction resulting in a hemodynamic collapse during generalized cold exposure. We report a case of a patient who developed CU and anaphylaxis during swimming and diving in the sea.