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

Even trace amounts of undeclared wheat can cause hives, swelling, respiratory distress, or life-threatening anaphylaxis in allergic individuals. —Martha McHardy, MSNBC Newsweek, 30 Aug. 2025

But Abby had gone through a terrifying episode of anaphylaxis while taking PEG-asparaginase. —Brenda Goodman, CNN, 29 Dec. 2022

Because of the risk of anaphylaxis that might require treatment by EpiPen, patients must remain under medical supervision for at least one hour after taking the treatment. —Denise Roland, WSJ, 29 Nov. 2022

Severe adverse reactions will lead to a complication called anaphylaxis that can be fatal. —Chris Smith, BGR, 1 Nov. 2022

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