anaphylaxis

What it means

1. countableuncountableExtreme sensitivity to a substance such as a foreign protein or drug.
2. countableuncountableA severe and rapid systemic allergic reaction to an allergen, causing a constriction of the trachea, preventing breathing; anaphylactic shock.

   He said a bite could send someone into anaphylaxis, which is a narrowing of the airways and lowering of blood pressure, within minutes.

   2025 August 16, Rylee Kirk, quoting William Sutton, “Hiker in Tennessee Who Picked Up a Venomous Snake Dies After Being Bitten”, in The New York Times, New York, N.Y.: The New York Times Company, →ISSN, →OCLC, archived from the original on 16 Aug 2025

   2 more examples

   “Anyone who has experienced or witnessed an anaphylaxis reaction knows it can be very stressful deciding when to inject epinephrine to themselves or a child and often delay,” Dr. Jonathan Spergel, chief of the allergy program at Children’s Hospital of Philadelphia, said in a news release from ARS Pharmaceuticals.

   2024 August 9, Meg Tirrell, “First nasal spray epinephrine drug for emergency allergic reactions gets FDA approval”, in CNN

   While we wait, she [Maggie Aderin-Pocock] reassures me that she always carries an EpiPen, and says she has recently become an ambassador for the Natasha Allergy Research Foundation, an allergy awareness charity named after teenager Natasha Ednan-Laperousse, who died from anaphylaxis in 2016.

   2025 December 20, Laura Battle, “Lunch with the FT: Maggie Aderin-Pocock”, in FT Weekend (Life & Arts section), London: The Financial Times Ltd., →ISSN, →OCLC, page 3

In a sentence

“Anyone who has experienced or witnessed an anaphylaxis reaction knows it can be very stressful deciding when to inject epinephrine to themselves or a child and often delay,” Dr. Jonathan Spergel, chief of the allergy program at Children’s Hospital of Philadelphia, said in a news release from ARS Pharmaceuticals.

2024 August 9, Meg Tirrell, “First nasal spray epinephrine drug for emergency allergic reactions gets FDA approval”, in CNN

Where it comes from

1. Frenchanaphylaxie
2. Englishanaphylaxis

Borrowed from French anaphylaxie, coined by French physiologist and parapsychologist Charles Richet and French zoologist Paul Portier from the Ancient Greek ᾰ̓νᾰ- (ănă-, “(intensifier) thoroughly”) from ᾰ̓νᾰ́ (ănắ, “to, again, upon”) and φύλαξις (phúlaxis, “protection, watching, guarding”).