Urticaria, commonly known as hives, usually strikes suddenly. First the skin itches, then it erupts into red welts. The itching may be severe, keeping people from working or sleeping. It s a distressing disorder which affects an estimated 20 percent of the population at one time or another in their lives. Most cases of urticaria are acute, lasting from a few hours to less than six weeks.
Some cases are chronic, lasting more than six weeks.
The welts may appear in one place, disappear after a short time, then erupt at another spot, then another. They are made worse by scratching. Each individual hive lasts no more than 24 hours.