What causes cold urticaria?
Cold urticaria is caused by exposure to cold. Why the cold stimulus causes the activation of mast cells and subsequent release of histamine and other inflammatory mediators remains unknown. The acquired form of cold urticaria may be primary (idiopathic) or secondary to an underlying haematologic (blood condition) or infectious disease. Most cases are of the idiopathic (unknown cause) type. Underlying conditions that have been associated with cold urticaria include cryoglobulinemia, chronic lymphocytic leukaemia, lymphosarcoma, chickenpox (varicella), viral hepatitis and infectious mononucleosis (glandular fever). Swimming in cold water is the most common cause of a severe cold urticarial reaction. Because of the potential risk of a severe reaction and subsequent drowning, all patients with cold urticaria should be supervised during aquatic activities.
