anaphylaxis

noun

ana·​phy·​lax·​is ˌa-nə-fə-ˈlak-səs 

plural anaphylaxes ˌa-nə-fə-ˈlak-ˌsēz 

1

: hypersensitivity (as to foreign proteins or drugs) resulting from sensitization following prior contact with the causative agent

2

: anaphylactic shock

Examples of anaphylaxis in a Sentence

Recent Examples on the Web

There's also a risk of anaphylaxis with a milk allergy. — Michele Laufik, Martha Stewart, 6 Feb. 2026

Although fatal anaphylaxis has been noted as a rare risk in severe cases, the New Jersey man’s death was the first to be attributed to the allergy. — Melissa Rudy, FOXNews.com, 14 Nov. 2025

Avoid triggers, but carry an epinephrine pen for emergency treatment of anaphylaxis for when triggers are unavoidable or unknown. — Ruth Jessen Hickman, Health, 12 June 2026

Food allergies are the leading cause of anaphylaxis, which is a sudden and potentially life-threatening allergic reaction. — Raven Brunner, PEOPLE, 31 May 2026

Word History

Etymology

New Latin, from ana- + prophylaxis

First Known Use

circa 1905, in the meaning defined at sense 1

Rhymes for anaphylaxis

• axis
• praxis
• taxus
• chemoprophylaxis
• chemotaxis
• epistaxis
• prophylaxis

Medical Definition

anaphylaxis

noun

ana·​phy·​lax·​is ˌan-ə-fə-ˈlak-səs 

plural anaphylaxes -ˌsēz 

1

: hypersensitivity (as to foreign proteins or drugs) resulting from sensitization following prior contact with the causative agent

2

: anaphylactic shock