All that heal disease stuff to survice, best is to never get slept..but as a new player it is hard to avoid it often.

If a potion fails, it means its spell is hindered by something and if you are slept by a necromancer it is likely you are cursed.

From the CURSE helpfile: "It also renders the character unclean in the eyes of the gods and unable to RECALL."

So your return potion will never work, and that is why you quaff a teleportation potoin instead.(This might be annoying as you dont know where your body will be if you are blinded and dies but that can be fixed by a mage locating it.)

So, teleport potions are always always nice to have. And else know where the closest healer(like town healer) is and run to him fast.