Victoria Simpson, age 9, of Great Falls, Mont., for her question:

WHAT CAUSES HIVES?

Hives are a form of skin rash that comes suddenly and disappears without leaving a trace. The rash consists of raised white welts that itch.

Hives may be caused by a food or drug to which the sufferer is hypersensitive. The patient may have an allergic reaction to some chemical he touches frequently, or to the fur of some pet or other animal.

Anyone's skin can be tested to discover the substance to which his body is allergic.

Hives may often be treated with antihistamine drugs or by bathing the spots with lotions of baking soda and water, witch hazel or some other cooling solution.

Hives are also known as nettle rash. The medical name for hives is urticaria. The names comes from the Latin word for nettle.