Binding of Isaac: Rebirth Wiki
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(except in Rebirth)

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

Effects[ | ]

  • (except in Repentance) -0.2 speed and maximum speed.
  • (in Rebirth and Afterbirth) -15 range.
  • (except in Repentance) +2.0 tear falling speed.
    • (in Rebirth and Afterbirth) The increased tear falling speed and decreased range results in slightly increased firing distance.
    • (in Afterbirth †) The increased tear falling speed and decreased range results in nearly identical 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.

Notes[ | ]

  • Tints tears red. This is only a cosmetic change.
  • Collectible Incubus iconIncubus will still fire tears normally while retaining the barrage effect, making this a good item for Character Lilith iconLilith.
    • The barrage from the Incubus will be in a straight line (similar to Collectible Cursed Eye iconCursed 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 (in Repentance) Character Tainted Lilith iconTainted Lilith.

Strategy[ | ]

  • 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.

Synergies[ | ]

  • Collectible Maw Of The Void iconMaw 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.
  • (in Repentance)Collectible Montezuma's Revenge iconMontezuma's Revenge/Collectible Revelation iconRevelation: Whenever the kidney stone is fired, the tear barrage will continuously charge and activate these items' effects until Isaac can fire normally.
  • (in Repentance)Collectible Rock Bottom iconRock Bottom: The temporary tears up from the kidney stone burst becomes a permanent x6 fire rate multiplier.

Interactions[ | ]

  • Collectible 20 20 icon20/20/Collectible The Inner Eye iconThe Inner Eye/Collectible Mutant Spider iconMutant Spider: Only fires one stone.
  • Collectible Anti-Gravity iconAnti-Gravity: The stone will not hover and will travel regardless.
  • Character Azazel iconAzazel/Collectible Brimstone iconBrimstone: Overrides Kidney Stone. (except in Repentance)Speed and range downs still apply.
  • (except in Repentance)Collectible Chocolate Milk iconChocolate Milk: When Kidney Stone activates, it fires one kidney stone and then no more tears until tears stat is under a certain value (unknown).
  • Collectible Cursed Eye iconCursed Eye: Charging the barrage pauses the Cursed Eye charge bar - if the bar is not full and Isaac is hurt, he will teleport. Firing during the barrage will neither fire tears, nor show the charge bar, but will still charge Cursed Eye. Being hit while the invisible charge bar is not full will teleport Isaac.
  • Collectible Dr. Fetus iconDr. Fetus: Overrides Kidney Stone. The range down ((in Repentance) or tear height down) is especially harmful with Dr. Fetus, making self-damage very likely.
  • Collectible Epic Fetus iconEpic Fetus: Overrides Kidney Stone.
  • (in Afterbirth † and Repentance)Collectible Compound Fracture iconCompound Fracture/Collectible Cricket's Body iconCricket's Body/Collectible The Parasite iconThe Parasite: The stone cannot split into smaller stones.
  • (in Afterbirth † and Repentance) Character The Forgotten iconThe Forgotten: The Forgotten will swing his club rapidly instead of shooting the burst of tears (The Forgotten still fires the stone normally).
  • (in Afterbirth † and Repentance)Collectible Haemolacria iconHaemolacria: Overridden by Haemolacria. (except in Repentance)Only stat changes apply.
    • (in Repentance)Fires a barrage of Haemolacria tears upon activation
  • (in Afterbirth † and Repentance)Collectible Jacob's Ladder iconJacob's Ladder: The stone will only spawn sparks when hitting enemies.
  • Collectible Libra iconLibra: Stats are greatly increased during the barrage. (except in Repentance)The harsh speed and range down make Libra a large stats down.
  • Collectible The Ludovico Technique iconThe Ludovico Technique: Overrides Kidney Stone.
  • Collectible A Lump of Coal iconA Lump of Coal: The stone will not grow bigger as it travels, but it will increase in damage.
  • Collectible Marked iconMarked: Occasionally, Isaac will stop automatically firing, and an attack key must be held to release the kidney stone and continue firing.
  • Collectible Mom's Knife iconMom's Knife: Overrides Kidney Stone.
  • Collectible Monstro's Lung iconMonstro's Lung: Overrides Kidney Stone.
    • When also having Collectible Technology iconTechnology, does not override, however the combination of the two items is not properly implemented and sometimes Kidney Stone will prevent Isaac from shooting.
  • (except in Repentance)Collectible Number One iconNumber One: Number One's range down overrides Kidney Stone, for an additional -0.62. The stone is not affected by the range decrease.
  • (in Repentance)Collectible Spirit Sword iconSpirit Sword: Overrides Kidney Stone.
  • (except in Repentance)Collectible Technology iconTechnology: Overrides Kidney Stone.
    • (in Repentance) Fires the stone like normal, followed by a barrage of Technology lasers.
  • (except in Repentance)Collectible Tech X iconTech X: Overrides Kidney Stone.
    • (in Repentance): Synergizes now, behaving pretty buggy however (look into "bugs" down below).
  • (in Repentance)Collectible Urn of Souls iconUrn of Souls: Firing the urn counts as fire time but the urn must be put away for Isaac to charge and shoot the kidney shot. Switching to the urn while auto-firing from Kidney Stone forces the urn to fire as well.

In-game Footage[ | ]

Trivia[ | ]

  • "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.
  • When Isaac enters a room with half a heart and holding this item, he will leave a small puddle of blood rather than pee.

Bugs[ | ]

Bug Bug! If Kidney Stone activates while a charged tear effect such as Collectible Tech X iconTech X or Collectible Chocolate Milk iconChocolate Milk is currently charging, the charge will get stuck, unable to fire for a somewhat-short period of time, before eventually having the Kidney stone be released as normal. Tears will then occasionally charge, even if a fire button isn't held down anymore.


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