Each wheal lasts a few hours before fading away, leaving no trace. New hives may continue to develop as old ones fade. They can vary in size from as small as a pencil eraser to as large as a dinner plate and may join together to form larger swellings. Hives are usually very itchy, but may also burn or sting. A number of different things including allergic reactions, chemicals in foods, or medications can cause histamine release.
Hives usually disappear within a few days to a few weeks.
Occasionally, a person will continue to have hives for many years. When hives form around the eyes or lips, the tissue may swell excessively. The term Angioedema is used to describe this type of swelling. Acute Urticaria Hives are classified according to how long the attacks last. With this type of hives, the cause can usually be identified and eliminated.