itching and dermatitis
skin disorders
Hives
Hives may or may not be an allergic reaction. For most people, a cause cannot be identified. If a cause is identified in hives that have lasted less than 6 weeks, the cause is usually an allergic reaction to a specific substance, an acute infection, or a nonallergic reaction to a specific substance. If hives have lasted 6 weeks or more, the cause usually cannot be identified (is idiopathic). People should call an ambulance if they have difficulty breathing or if their throat feels as if it is closing up. People with mild symptoms should avoid any known or suspected triggers and can take antihistamines to relieve symptoms. People who have severe reactions should carry a self-injectingepinephrinepen and, if a reaction occurs, use it immediately. 