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What causes allergy symptoms?

Dr. Michael Roizen, MD
Internal Medicine
An allergy is an overreaction by the immune system to some type of allergen that the body is exposed to.

When that invader enters the body, often through the nose, the body tries to protect itself by producing those antibodies called immunoglobulin E (IgE). That sets off a chain reaction in which IgE sends a signal to allergy cells (mast cells) to release chemicals that fight the allergen. When those chemicals (some are called histamines; others belong to the cytokine system) are released into the bloodstream, they produce inflammatory reactions throughout the body, not just at the site of invasion. It's those reactions that trigger the itchy eyes, the runny nose, the hives, etc.
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YOU: Raising Your Child: The Owner's Manual from First Breath to First Grade

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.