'antianaphylaxis' originates from a modern medical formation combining the prefix 'anti-' (from Greek 'anti-' meaning 'against') and the noun 'anaphylaxis' (from Greek 'anaphylaxis'), where 'anti-' meant 'against' and 'anaphylaxis' referred to a severe allergic reaction coined from Greek elements.

'antianaphylaxis' was formed by prefixing 'anti-' to the already established medical term 'anaphylaxis' (which entered scientific usage in the early 20th century via French 'anaphylaxie' from Greek elements 'ana-' + 'phylaxis'), producing a modern English term meaning action against anaphylaxis.

Initially formed to mean literally 'against anaphylaxis', its practical meaning settled as 'the prevention or counteraction of anaphylactic reactions' in medical contexts.