anaphylactic shock

UK: /ˌænəfɪˈlæktɪk/

WordReference Random House Unabridged Dictionary of American English © 2025

an′aphylac′tic shock′, 

1. Pathology a severe and sometimes fatal allergic reaction to a foreign substance, esp. a protein, as serum or bee venom, to which an individual has become sensitized, often involving rapid swelling, acute respiratory distress, and collapse of circulation.

• 1905–10

Collins Concise English Dictionary © HarperCollins Publishers::

anaphylactic shock noun

1. a severe, sometimes fatal, reaction to a substance to which a person has an extreme sensitivity, often involving respiratory difficulty and circulation failure