Debuffs

 are a feature first introduced in patch 1.0.6. bestow negative effects upon their bearers, and, unlike buffs, cannot be removed by right-clicking on their icons. Some monsters can be infected with certain debuffs, including Confused, Cursed Inferno, On Fire! and Poisoned.

will naturally wear off after a short period of time, though some may last up to a few minutes. The Nurse can cure debuffs at the cost of  per debuff.

Table
1The following monsters can inflict the On Fire! debuff: Fire Imp (Burning Sphere), Lava Slime, Meteor Head, Skeleton Archer (Flaming Arrows)

2The following weapons can inflict the On Fire! debuff: Fiery Greatsword, Flamarang, Flamelash, Flamethrower, Flaming Arrow, Flower of Fire, Molten Fury, Molten Hamaxe, Molten Pickaxe, Sunfury

3The following weapons can inflict the Poisoned debuff: Blade of Grass, Poisoned Knife, Thorn Chakram

4The following healing items will inflict the Potion Sickness debuff: Bottled Water, Glowing Mushroom, Goldfish, Greater Healing Potion, Healing Potion, Lesser Healing Potion, Lesser Restoration Potion, Mushroom, Restoration Potion

Bugs

 * When curing the Potion Sickness debuff via the Nurse, the icon disappears but the actual effects of the debuff are not removed.