'autointoxicant' is a modern English compound formed from the Greek prefix 'auto-' (from Greek 'autos' meaning 'self') and the word 'intoxicant' (from Medieval/Modern English, itself from Latin/French roots related to 'toxin' and 'intoxicate').

'intoxicant' derives from 'intoxicate' (Late Latin/Medieval Latin intoxicare and Old French forms) and ultimately from Greek 'toxikon' (poison). The compound 'autointoxicant' arose in English usage alongside the medical term 'autointoxication' in the late 19th to early 20th century.

Initially, terms related to 'intoxicant' meant 'a substance that causes intoxication (poisoning)'; 'autointoxicant' specifically came to denote substances produced within the body thought to cause self-poisoning—usage born from medical theories of autointoxication, and today it is used more generally for endogenous toxins.