You needn't, however, spend your life's savings to clear out the substances that trigger allergic reactions. Troublesome agents can be controlled, avoided and even banished without choking your budget.

In an allergy, the body produces a substance called immunoglobulin E when exposed to an allergen, said Dr. Wendell Richmond, assistant professor of allergy and immunology in the microbiology section of Rush-Presbyterian-St. Luke's Medical Center.

Protein is a substance to which people "almost always make allergic antibodies," said Dr. Roy Patterson, chairman of the Department of Medicine and chief of the allergy section at Northwestern University Medical School. Those of particular importance in a home, Patterson said, are: