Urticaria, or hives, is a condition in which red, itchy, and swollen raised areas appear on the skin--usually as an allergic reaction from eating certain foods or taking certain medicines; however, sometimes the cause may be unknown. Hives can vary in size from one-half inch to several inches in size. Hives can appear all over the body or be limited to one part of the body.
Antibiotics, especially penicillin and sulfa-based drugs
Anticonvulsant drugs or antiseizure drugs
Dermatographism. Hives caused by scratching the skin, continual stroking of the skin, or wearing tight-fitting clothes that rub the skin.
Cold-induced. Hives caused by exposure to cold air or water.
Solar hives. Hives caused by exposure to sunlight or light bulb light.
Exercise-induced urticaria. Allergic symptoms brought on by physical activity.
Chronic urticaria. Recurrent hives with no known cause.
Angioedema is an allergic reaction that causes swelling deeper in the layers of the skin. It most commonly occurs on the hands, feet, and face (lips, tongue, and eyes).