Halle Berry
Halle Berry. Photo by Gage Skidmore, CC BY-SA 3.0, Link

Asthma and Allergy Foundation of America

Allergies are diseases of the immune system that cause an overreaction to substances called “allergens.” Allergies are grouped by the kind of trigger, time of year or where symptoms appear on the body: indoor and outdoor allergies (also called “hay fever,” “seasonal,” “perennial” or “nasal” allergies), food and drug allergies, latex allergies, insect allergies, skin allergies and eye allergies. People who have allergies can live healthy and active lives.