Binding of Isaac: Rebirth Wiki
Binding of Isaac: Rebirth Wiki

Added in Afterbirth

Kidney Stone is an unlockable passive item added in The Binding of Isaac: Afterbirth.


  • Removed in Repentance -0.2 speed and maximum speed.
  • Removed in Repentance -17 range.
  • Removed in Repentance +2.0 tear height.
    • Removed in Repentance The increased tear height and decreased range results in overall slightly less firing distance.
  • Occasionally, firing tears will cause Isaac to charge an attack with his head pulsating with a red color. After the attack has charged up, the fire button can be released to fire a kidney stone that does 5 times Isaac's damage and pierces enemies, followed by a rapid, inaccurate spray of tears.
    • This effect occurs approximately every 25 seconds.
    • Isaac won't be able to fire tears normally until the kidney stone has been fired.
    • The kidney stone has approximately twice the range of normal tears.
    • The barrage will continue for its full length between rooms, as will the state of charging the attack instead of firing tears.
  • When Isaac has half a heart left, the urine that appears underneath Isaac upon entering rooms will be changed to red.


  • Activating this item before entering a difficult room, like a boss room, can allow you to deal a lot of damage right away. To do this, simply hold the attack button until you stop shooting tears.


  • Tints tears red. This is only a cosmetic change.
  • Incubus Incubus will still fire tears normally while retaining the barrage effect, making this a good item for Lilith Lilith.
    • The barrage from the Incubus will be in a straight line (similar to Cursed Eye Cursed Eye) instead of an inaccurate burst.
    • The kidney stone itself will come out of Lilith, not the Incubus follower, even though she cannot fire tears. The barrage of tears will still only come from the Incubus. This also applies if blindfolded as another character.
    • This is the only item to be able to override the Grayscale easter egg.
    • This item does not appear to work at all for Added in Repentance Tainted Lilith Tainted Lilith.


  • Maw of the Void Maw of the Void: Whenever the kidney stone is fired, the tear barrage will continuously charge and activate Maw of the Void until Isaac can fire normally.
  • Added in RepentanceRock Bottom Rock Bottom: The temporary tears up from the kidney stone burst becomes a permanent x6 fire rate multiplier.


  • 20/20 20/20/The Inner Eye The Inner Eye/Mutant Spider Mutant Spider: Only fires one stone.
  • Anti-Gravity Anti-Gravity: The stone will not hover and will travel regardless.
  • Azazel Azazel/Brimstone Brimstone: Overrides Kidney Stone. Speed and range downs still apply.
  • Chocolate Milk Chocolate Milk: When Kidney Stone activates, it fires one kidney stone and then no more tears until tears stat is under a certain value (unknown).
  • Dr. Fetus Dr. Fetus: Overrides Kidney Stone. The range down is especially harmful with Dr. Fetus, making self-damage very likely.
  • Epic Fetus Epic Fetus: Overrides Kidney Stone.
  • Added in Afterbirth †Compound Fracture Compound Fracture/Cricket's Body Cricket's Body/The Parasite The Parasite: The stone cannot split into smaller stones.
  • Added in Afterbirth † The Forgotten: The Forgotten will swing his club rapidly instead of shooting the burst of tears (The Forgotten still fires the stone normally).
  • Added in Afterbirth †Haemolacria Haemolacria: Overridden by Haemolacria. Only stat changes apply.
    • Added in RepentanceFires a barrage of Haemolacria tears upon activation
  • Added in Afterbirth †Jacob's Ladder Jacob's Ladder: The stone will only spawn sparks when hitting enemies.
  • Libra Libra: Removed in Repentance The harsh speed and range down make Libra a large stats down. Stats are increased during the barrage.
  • The Ludovico Technique The Ludovico Technique: Overrides Kidney Stone.
  • A Lump of Coal A Lump of Coal: The stone will not grow bigger as it travels, but it will increase in damage.
  • Marked Marked: Occasionally, Isaac will stop automatically firing, and an attack key must be held to release the kidney stone and continue firing.
  • Mom's Knife Mom's Knife: Overrides Kidney Stone.
  • Monstro's Lung Monstro's Lung: Overrides Kidney Stone.
  • Number One Number One: Number One's range down overrides Kidney Stone, for an additional -0.62. The stone is not affected by the range decrease.
  • Added in RepentanceSpirit Sword Spirit Sword: Overrides Kidney Stone.
  • Technology Technology: Overrides Kidney Stone.
    • Added in Repentance Fires the stone like normal, followed by a barrage of Technology lasers.
  • Tech X Tech X: Overrides Kidney Stone.
    • Added in Repentance: Synergizes now, behaving pretty buggy however (look into "bugs" down below).
  • Added in RepentanceRevelation Revelation: The laser fires automatically at intervals during the tear spray, regardless of whether or not you are holding the fire button.

In-game Footage[]


  • "Matt" refers to Matt Kap, a pixel artist for The Binding of Isaac: Rebirth, who has once been afflicted with a kidney stone.
    • A kidney stone is a hard deposit made of minerals and salts that form inside kidneys. It will usually pass through the urethra, which is often a very painful process.


PC Normal and hard modes only ZX84 DLBX (First floor Treasure Room)


Bug Bug! If Kidney Stone's comes available while Tech X Tech X is currently charging the chargebar will get stuck, as well as the animation. For some time tears cant be fired, a little later (often suspicously long) Kidney Stone will be bursted out normally. The charge up then sometimes happenes, even if the fire-button isn't hold down anymore.