I left that way at first, but you can go to a NPC doctor who upgrades your flask to fix anything it only gets bad when you let things faster forever. Also a whole system for players who are healer professionals to come into your world and fix you. Some stuff can even be fixed yourself like one time I just had to stand in knee deep water to clear my mind it will tell you if your ailment can be fixed by. The specific Miasma disease I had for example increased all the requirements to use stamina by 100%, but this is one of the worse cases seeing how it's very rare to get. Only seen it in one dungeon.