1. Health
Send to a Friend via Email

Allergen

By

Updated February 08, 2008

Definition: An allergen is any normally harmless substance that causes a reaction in an allergic person. The immune system of a person with allergies responds to an allergen in much the same way the immune system normally responds to a germ, or antigen.
Pronunciation: AHL-er-jen
Also Known As: allergy trigger
Examples:
For someone with a dairy allergy, milk is an example of an allergen.
Related Video
USDA Food Pyramid Explained
  1. About.com
  2. Health
  3. Food Allergies
  4. Glossary
  5. Allergen - Definition of Allergen

©2014 About.com. All rights reserved.

We comply with the HONcode standard
for trustworthy health
information: verify here.