Urticaria, also called nettle rash or hives, is one of the most common skin diseases. In general, the term "urticaria" is preferred, since it is understood internationally and because affected patients are not really suffering from contact with stinging nettles.
Roughly one in four people will experience urticaria at some point in their lives. These episodes generally last only a few days or weeks and are unproblematic. These are referred to as acute urticaria. Much more troublesome (to bear and to treat) are urticarias that last for several months or years (or even decades). These are referred to as chronic urticaria.
The name urticaria actually derives from the stinging nettles (Latin: Urticaria dioica or Urticaria urens); most likely because the hives on the skin look similar to those found when someone is "stung" by nettles.