'antitoxic' is formed in modern English from the Greek prefix 'anti-' meaning 'against' + the adjective 'toxic' (from Late Latin/Greek 'toxicum'/'toxikon', meaning 'poison').

'toxic' derives from Latin 'toxicum' and Greek 'toxikon' (originally referring to a poison for arrows from 'toxon' = 'bow'), and the combining form 'anti-' (Greek 'anti') was attached in modern English usage to create 'antitoxic' (19th–20th century medical formation).

Initially built to mean 'acting against a poison' in medical contexts, its usage has remained focused on either 'neutralizing toxins' or, more generally, 'non-toxic/harmless' in some contexts.