Allergies and Hypersensitivities
A llergy is a broad term used to describe an unusual reaction of the body's tissues to a substance that has no noticeable effect on other persons. About 17 out of every 100 persons in America are allergic, or hypersensitive, to one or more substances that are known to precipitate an unusual reaction. Such substances, known as allergens , include a variety of irritants, among them mold spores, pollens, animal dander, insect venoms, and house dust. Some individuals are allergic to substances in soap, which produce a skin irritation. Others react to the smell of a rose by sneezing. Still others react with an outbreak of hives, diarrhea, or other symptoms to allergens in foods.