Hives – red, splotchy, itchy, raised patches or welts that seem to "bloom" suddenly on the skin – are quite common in both children and adults. About 10 to 25 percent of people will get them at least once during their lives. The welts typically move from place to place on the body. Hives usually itch, but they also can burn or sting.
Hives, also known as urticaria, can happen at any time in life and can be triggered by an allergic reaction to foods, medications, pets, or insect bites. Other causes include viral infections, illnesses, and hormonal changes. Stress is also thought to be a factor, although stress is very hard to measure, so there are no definitive studies on the effect of stress on hives.
No matter what the cause, a case of hives can last for a few minutes, a few hours, or even days. Hives can manifest as acute flare-ups or occur on a chronic basis. Chronic daily hives, defined as lasting longer than six weeks, are much more common in adults, although they do occur in children. Unless children experience prolonged hives, we usually don't test for an underlying cause. It's simply more expedient to treat them, since the testing is usually not very helpful.
When children have chronic hives, we will test for underlying causes, such as autoimmune diseases, herpes simplex virus, hepatitis C, and thyroid disorders. But even in patients with chronic hives, it is only in about 5 percent of cases are we able to identify an underlying cause for the hives. Consequently, chronic hives (chronic idiopathic urticaria) are very frustrating and puzzling, as well as difficult to treat.
To relieve hives, we'll first try a non-sedating, non-steroidal long-acting antihistamine such as loratadine or cetirizine, giving one dose twice a day. If symptoms don't abate, we go on to diphenhydramine or another antihistamine which is usually effective, but does contain a mild sedative. Only if these antihistamines fail do we move on to steroid treatment. We always try to get results with the safest medications first because of the known side effects associated with steroids. A relatively recent drug called omalizumab, has been showing some positive results.
Also uncommon, but not unheard of, are hives that happen when a person is exposed to cold or heat (water, ice, weather, etc.) or pressure, such as when carrying a backpack. This type of hives is known as physical urticaria and the best treatment is avoidance of the triggers. Antihistamines would also work to control symptoms if they occur.