"Doctor up" is a phrasal verb that means to improve or fix up something or someone. The antonyms for this expression include terms such as worsen, damage, ruin, harm, spoil, worsen, and destroy. The opposite of doctoring up something could be leaving it the way it is or not doing anything to enhance it. For instance, leaving a worn-out car without any repairs amounts to not doctoring it up. Similarly, if a severely ill patient is left unattended, it would be the opposite of doctoring them up. In conclusion, the antonyms for "doctor up" emphasize the negative impact of not taking steps to improve things.