Mithridatization

Mithridatization is the practice of protecting oneself against a poison by gradually self-administering non-lethal amounts. The word derives from Mithridates VI, the King of Pontus, who so feared being poisoned that he regularly ingested small doses in the hope of developing immunity. Having been defeated by Pompey, Mithridates attempted to kill himself with poison - but his mithridization proved too successful, and he was compelled to order a mercenary to stab him to death.