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Urticaria, also known as hives, is an outbreak of swollen, pale red bumps orplaques (wheals) on the skin that appear suddenly --either as a result of the body's adverse reaction to certain allergens, or forunknown reasons.
Hives usually cause itching, but may also burn orsting. They can appear anywhere on the body, including the face, lips, tongue,throat, or ears. Hives vary in size (from a pencil eraser to a dinner plate),and may join together to form larger areas known as plaques. They can last forhours, or up to one day before fading. Read more about hives (urticaria and angioedema).