Urticaria (from the
Latin urtica, "nettle" from
urere, "to burn"), commonly referred to as
hives, is a kind of
skin rash notable for pale red, raised, itchy bumps. Hives may cause a burning or stinging sensation. They are frequently caused by
allergic reactions; however, there are many nonallergic causes. Most cases of hives lasting less than six weeks (acute urticaria) are the result of an allergic trigger. Chronic urticaria (hives lasting longer than six weeks) is rarely due to an allergy.