allergen

noun

al·​ler·​gen ˈa-lər-jən 

: a substance (such as pollen) that induces allergy

allergenic

ˌa-lər-ˈje-nik 

adjective

allergenicity

ˌa-lər-jə-ˈni-sə-tē 

noun

Examples of allergen in a Sentence

common allergens, such as pollen

Recent Examples on the Web

The recall was initiated after it was discovered that packaging did not declare milk in the allergen statement. —Deputy News Editor, MSNBC Newsweek, 22 Nov. 2025

Five major food and medication recalls made headlines this month, for reasons ranging from undeclared allergens and bacterial contamination to unapproved ingredients and failed drug requirements. —Jenna Anderson, Health, 21 Nov. 2025

If allergies seem to worsen when near the couch, a professional cleaning can help remove trapped allergens. —Karen Brewer Grossman, Southern Living, 21 Nov. 2025

Because allergen reactions can escalate quickly — and because packaged foods are a frequent source of accidental exposure — accurate labeling is critical. —Moná Thomas, PEOPLE, 20 Nov. 2025

Word History

Etymology

borrowed from German Allergen,, blend of allerg- (in Allergie allergy) and -gen (in Antigen antigen)

Note: See note at allergy.

First Known Use

circa 1907, in the meaning defined above

Kids Definition

allergen

noun

al·​ler·​gen ˈal-ər-jən 

: a substance (as pollen) that causes allergy

allergenic

ˌal-ər-ˈjen-ik 

adjective

Medical Definition

allergen

noun

al·​ler·​gen ˈal-ər-jən 

: a substance that induces allergy

inhaled allergens

a suspected food allergen