The immune system normally responds to harmful substances such as
bacteria, viruses and toxins by producing symptoms such as runny
nose and congestion, post-nasal drip and sore throat, and itchy
ears and eyes. An allergic reaction can produce the same symptoms
in response to substances that are generally harmless, like dust,
dander or 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: 08/11/2010
Reviewed By: Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La
Jolla, California. Also reviewed by David Zieve, MD, MHA, Medical
Director, A.D.A.M., Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)
