Hives are an allergic reaction of the skin that may last a few minutes or can persist for a few days. They appear as raised, red, itchy bumps of different shapes and sizes, with defined red margins and pale centers.

Hives may appear and then disappear at random and seem to move from place to place on the skin.

Hives may appear as a reaction to a medication, food, or infection. A single area of swelling often occurs after an insect bite at the site of the bite. Other possible causes include skin contact with animal saliva, plants, or latex. Often a cause cannot be found.

Hives are often minor, but they can also be the first sign of a life-threatening allergic reaction (anaphylaxis) that requires emergency care.