Hemoptysis

Hemoptysis is a passive item added in The Binding of Isaac: Repentance.

Effects[]

Double-tapping a fire button causes Isaac to sneeze blood, dealing damage to enemies in front of him. The sneeze deals damage equal to 1.5x Isaac's damage and pushes enemies and their projectiles back. If the enemy is pushed into a wall/obstacle, they take 10 damage and deal 10 damage to enemies they collide with.
- The sneeze has a cooldown of 1 second.

Tainted Azazel has a mechanic similar to Hemoptysis.
- This version of Hemoptysis allows him to deal full brimstone damage to enemies, which were damaged with sneeze before.
The sneeze's range is affected by the shot speed stat, and not by the range stat itself.
The sneeze can push Bombs.
The collision damage can be used to damage Hosts while their skulls are lowered.

Azazel / Tainted Azazel / Brimstone / Lil Brimstone / Trisagion / Montezuma's Revenge / Brimstone Bombs / Maw of the Void / Lil Abaddon / Athame: Damage dealt by Brimstone or Brimstone-like beams is doubled on targets that have been sneezed on. The vulnerability is indicated by a faint red tint.
- The tint is still visible on Champion enemies, and enemies under status effects.
Fire Mind: The sneeze will still set enemies on fire, but not cause explosions, similar to its interaction with Brimstone.
Loki's Horns: Chance to sneeze in all cardinal directions.
Lost Contact: The sneeze reflects enemy shots.
Monstro's Lung: Multiple sneezes are applied around the character.
The Wiz: Shoots two sneezes diagonally instead of one straight forward.

Ipecac: The sneeze causes an explosion if used close against a wall or a stationary object.