Medicine Cabinet: Frustration in treating hives

I've been diagnosed with systemic idiopathic urticaria (hives). I've had recurrent hives and welts, sometimes covering 80 percent of my body, for more than two months. I have been taking hydroxyzine (Atarax), 25 mg every four hours, without any change. I have seen an allergist and tried cutting out certain foods. That hasn't helped. Any suggestions?

Urticaria is often an incredibly frustrating condition. When hives keep occurring for more than six weeks, as yours have, doctors call that chronic urticaria. The cause of chronic urticaria is found in a small percentage of patients.

Urticaria is an allergic reaction. When doctors cannot identify the underlying cause after a diagnostic evaluation, we refer to the condition as idiopathic urticaria. I suspect you and your doctors have considered more common causes besides food and environmental allergens, including:

Medications, including herbs, supplements and over-the-counter drugs

Bug bites

Physical causes, such as pressure, cold or hot temperatures, sun exposure

Exercise, as the skin gets sweaty

You probably have had a lot of blood tests. They usually don't point to a cause. Even a skin biopsy won't provide a specific answer. But it may be worthwhile to have a skin biopsy to exclude a rare condition called urticarial vasculitis.

Dermatologists believe many patients given the diagnosis of idiopathic urticaria in the past had a form of an autoimmune disorder. For unknown reasons, a person's immune system reacts against his or her own skin.

People with persistent urticaria often need higher-than-usual doses of antihistamines. You may need to try a few combinations of antihistamines. The antidepressant doxepin has potent antihistamine properties. It is sometimes effective when more traditional antihistamines have not controlled hives.

Corticosteroids such as prednisone may be needed. Because of side effects, doctors try to use the smallest dose for the shortest time. The good news is that, most often, the hives stop, but how long yours will persist cannot be predicted. Keep working with your doctors.