Real Dictionary

anaphylactic shock in American English
noun: 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

anaphylactic shock in British English
noun: a severe, sometimes fatal, reaction to a substance to which a person has an extreme sensitivity, often involving respiratory difficulty and circulation failure

anaphylactic shock in the Pharmaceutical Industry
noun: Anaphylactic shock is a catastrophic allergic reaction to a substance.