WEDNESDAY, March 24 (HealthDayNews) -- To hive or to hive not.

That's the subject of an article in the March issue of the Mayo Clinic Health Letter that outlines some of the causes and treatments for hives.

Many foods -- including milk, eggs, fresh berries, nuts, or fish -- can cause hives. They're red, raised and itchy welts that can be as small as a pencil eraser and as large as a dinner plate. They usually last less than 24 hours. But hives can also last for days, weeks, months, or even years.

Insect bites, medications, infections, and scratching your skin can also cause hives.

It's often difficult to identify the cause of chronic hives, those that last more than six weeks. The cause of chronic hives is identified in only about 10 percent of cases.

People with mild hives may get relief by taking cool showers, using over-the-counter antihistamines, or by applying cool compresses to the affected area.

A severe attack of hives may require emergency care.

More information

The American Academy of Dermatology has more about hives.