I came across this phrase in Tokyo Ghoul (東京喰種グール) which is apparently used a lot by nurses/doctors when talking to patients:

入院中にお酒なんて、絶対 ダメなんです。

Drinking while in hospital is not allowed! You won’t heal properly if you keep doing that.

It’s quite a strong phrase that literally means, “the things that are supposed to heal properly, won’t heal”. 酒を飲まなきゃ治るものも、飲んでたら治らない. Compared to the simple 治らないですよ, it’s a stronger, more 説教 expression and more likely to be used by angry or impatient people :)