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 plans follow cross-party support for Benedict's Law, a campaign to improve allergy safety in schools by ensuring consistent, life-saving protections for children with food allergies and anaphylaxis.

From BBC • Mar. 5, 2026

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

Elysia did not develop anaphylaxis - a severe and life-threatening allergic reaction - but she did need to be treated.

From BBC • Jul. 12, 2025

The term anaphylaxis is applied to an allied condition of supersensitiveness which appears to be induced by the injection of certain substances, including toxins and sera, that are capable of acting as antigens.

From Manual of Surgery Volume First: General Surgery. Sixth Edition. by Thomson, Alexis