Urticaria is a medical term for hives, a common allergic reaction that affects about 20% of people at some point in their lives.

There are many triggers for hives, but the symptoms include itchy patches of skin that become swollen, red welts. Itching can be mild to severe and may be made worse by scratching, alcoholic beverages, exercise, and stress.

Many people are aware of their triggers for hives, such as eating foods including shrimp or peanuts, which cause an allergic reaction within a short time. For others, there are so many possible causes of hives it requires allergy testing by a physician, and in some cases, the cause may never be identified.