anaphylaxis

American  

[an-uh-fuh-lak-sis] / ˌæn ə fəˈlæk sɪs /

noun

Pathology.

1. exaggerated allergic reaction to a foreign protein resulting from previous exposure to it.

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anaphylaxis British  

/ ˌænəfɪˈlæksɪs /

noun

1. extreme sensitivity to an injected antigen, esp a protein, following a previous injection

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anaphylaxis Scientific  

/ ăn′ə-fə-lăk′sĭs /

1. See anaphylactic shock

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Other Word Forms

• anaphylactic adjective
• anaphylactically adverb
• antianaphylactic adjective
• pseudoanaphylactic adjective

Etymology

Origin of anaphylaxis

First recorded in 1905–10; ana- + (pro)phylaxis

Compare meaning

How does anaphylaxis compare to similar and commonly confused words? Explore the most common comparisons:

• anaphylaxis vs. anaphylactic shock

Example Sentences

The immune system tries to fight them off, triggering symptoms ranging from hives and diarrhea to anaphylaxis, a life-threatening condition.

From Los Angeles Times • Oct. 20, 2025

Among the most common co-occurring illnesses were chronic fatigue syndrome and mast cell activation syndrome, or MCAS, a condition where patients experience intense episodes of diarrhea, hives, vomiting, and, in many cases, life-threatening anaphylaxis attacks.

From Slate • Sep. 15, 2025

People at risk of potentially life-threatening allergic reactions, known as anaphylaxis, should always carry two adrenaline pens.

From BBC • Oct. 16, 2024

But review author Prof Paul Turner, clinical professor in anaphylaxis and paediatric allergy at Imperial College London, said passengers should not worry about food being transmitted in the air.

From BBC • Oct. 16, 2024

A condition known as anaphylaxis or hypersensitiveness, which at present is being much studied, may sometimes occur in the human being.

From Health on the Farm A Manual of Rural Sanitation and Hygiene by Harris, H. F. (Henry Fauntleroy)