Hives are raised red bumps on the skin most often caused by an allergic reaction. Hives usually cause itching, but may also burn or sting. They can appear anywhere on the body, including the face, lips, tongue, throat, or ears. Hives vary in size (from the size of a pencil eraser to that of a dinner plate), and may join together to form larger areas known as plaques. Occasionally, hives can signal more serious problems, especially when accompanied by symptoms such as difficult breathing. Follow the links below to find WebMD's comprehensive coverage of hives, what they look like, how to treat them, and much more.