Allergic rhinitis, or hay fever, is a collection of symptoms, predominantly in the nose and eyes, to allergens such as dust, dander and pollen. The sensitized immune system produces antibodies to these allergens, which cause chemicals called histamines to be released into the bloodstream, causing itching, swelling of affected tissues, mucus production, hives, rashes, and other symptoms. Symptoms vary in severity from person to person.

Review Date: 7/5/2002 12:00:00 AM Reviewed By:A.D.A.M. Medical Illustration Team

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