Lasting for minutes or days, hives (also called wheals or welts) are large, itchy red bumps on the skin. Hives can also last for a longer period and are then referred to as chronic urticaria.

These hives can be one or many bumps, and vary greatly in size and shape. Although they more commonly appear on the arms, legs and trunk, they can appear anywhere on the body as a result of the body’s reaction to factors such as certain foods, pollen, animal dander, drugs, insect bites, cold, heat, light or emotional stress. Histamine causes the hives to form.

Hives are generally not an emergency, but when they appear suddenly, spread rapidly and are accompanied by a swollen throat, tightness of the chest, wheezing or difficulty breathing, this indicates a severe allergic reaction that requires immediate medical attention.