'antitoxin' originates from Greek elements via modern medical coinage: the prefix 'anti-' (from Greek 'anti' meaning 'against') plus 'toxin' (from Greek 'toxikon' meaning 'poison').

'antitoxin' was coined in the late 19th century in medical and scientific contexts (notably in German as 'Antitoxin' in immunology work by researchers such as Emil von Behring) and was adopted into English as 'antitoxin'.

Initially it referred specifically to therapeutic sera used against particular diseases' toxins (for example diphtheria); over time it has come to mean more generally any antibody or serum that neutralizes a toxin.