Razor Blade

Razor Blade is an unlockable activated item.

Effect[]

On use, takes a full red heart of health and grants +1.2 damage for the current room.

Eve starts with this item after unlocking it and donating 439 coins to the Greed Machine.
- Both conditions must be met for Eve to hold it; donating 439 coins before defeating Satan with Eve will wrongly state on Eve's profile on the Character Selection Screen that she has it equipped.
  - Eve now starts with the Razor Blade if unlocked from the Greed Machine, even if Satan has not been defeated with Eve.
If Isaac doesn't have a full Red Heart or a filled Bone Heart, then Soul, Black, and empty Bone Hearts are taken instead.
The effect stacks with itself and Red Patch, which provides a similar benefit.
Using this item does not affect Devil or Angel room chances.
Using this item as The Lost will result in death.
When picked up, Isaac's tears turn red, though this change is purely cosmetic.
The Razor Blade prioritizes Red Hearts first.
- Using the Razor blade grants Isaac the regular immunity frames upon usage; this allows Isaac to enter cursed rooms without using soul hearts should he have them.
Using this item in the Greed mode Ultra Greed boss room will result in Isaac losing 2-4 coins and dropping 1-3 pennies on the floor similar to being hit by any of the greed enemies.

Isaac's Heart: Isaac cannot take damage from the Razor Blade, allowing for infinite uses of the item.
Old Bandage / Shard of Glass: Isaac has a chance to drop a red heart while using the item.
Panic Button: Self-damage occurs before enemy damage, making it almost impossible to lose Angel or Devil chance.
The Polaroid: Isaac takes no damage while invincible, allowing for repeated free uses of the item.
The Wafer: Isaac loses half a heart instead of a full heart.
Whore of Babylon: The Razor Blade can be used to activate this item's effect by doing enough damage to get Isaac down to half a red heart (or one red heart as Eve), providing a big damage boost for the current room at the cost of health.

Car Battery: No effect.
Shield/Invulnerability: Will not protect against this item's damage.
Tainted Samson: Using this item can make Tainted Samson unkillable, as his Berserk timer gains time when damaged, and he can't die from lack of red hearts during the rage.

This item is used in Darkness Falls (challenge #4).
The item itself is a reference to the act of cutting one's self, usually at the wrists, to inflict self-harm or to commit suicide by loss of blood.
Isaac's appearance after using the item is just like the Dople.
In the original The Binding of Isaac, Razor Blade was unlocked by defeating Mom's Heart/It Lives as Eve.

Bug!	As Eve, there is a very unlikely chance that using this to activate Whore of Babylon will not activate it, despite being at the correct health to do so.