'pseudoanaphylactic' originates from Greek elements: the prefix 'pseudo-' (from Greek 'ψευδής', meaning 'false') combined with 'anaphylactic' (from 'anaphylaxis'). 'pseudo-' meant 'false', and 'anaphylactic' relates to 'anaphylaxis'.

'pseudoanaphylactic' was coined in modern medical English (20th century) by combining the prefix 'pseudo-' with the existing medical adjective 'anaphylactic' (from 'anaphylaxis') to describe reactions that resemble but are not true IgE-mediated anaphylaxis.

Initially, the composite literally meant 'false anaphylactic' (i.e., not true anaphylaxis). Over time it has been used more specifically to denote anaphylaxis-like, non–IgE-mediated reactions (anaphylactoid or pseudo-allergic responses).