Each year I see hundreds of new patients with complaints of hives and swelling. Hives are intensely itchy skin rashes that resemble welts and can occur anywhere on the body. They typically arise without warning and about half the time, are accompanied by angioedema, a deeper swelling in the skin. "Urticaria" is the technical term for hives. These skin eruptions generally last for several hours but rarely for more than twenty four hours. Hives which come and go for more than six weeks are...