Advertisement

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.
YOU: Raising Your Child: The Owner's Manual from First Breath to First Grade

More About this Book

YOU: Raising Your Child: The Owner's Manual from First Breath to First Grade

There’s little doubt that parenting can be one of the most rewarding and satisfying experiences you’ll ever have. But it can be plenty tough, too: Around the clock, you’re working to keep your...

Continue Learning about Allergies Causes & Risk Factors

What foods can commonly cause skin allergies?
Diana MeeksDiana Meeks
Eating certain foods can cause skin allergy symptoms like hives or rashes. Some of the most common f...
More Answers
What causes allergic reactions?
American Red CrossAmerican Red Cross
Allergic reactions are caused by overactivity of the immune system against specific foreign subs...
More Answers
Kids, Food Allergies and Bullying
Kids, Food Allergies and Bullying
Are Allergies Inherited?
Are Allergies Inherited?

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.