A silver, sharp razor blade.
Allows trading hearts for more damage in the current room upon each activation.
Isaac pays a full heart in normal state but half a heart while recovering from damage (Isaac blinking). Basic Damage is increased by 1.2. Final Damage increment on each use decreases with the number of repeated usages because of the square root "soft cap" in the damage formula.
Pays Soul Hearts if Isaac has less than one full Red Heart. Otherwise, it takes Eternal Hearts first, then Red Hearts.
- Items that grant temporary invulnerability like Celtic Cross or The Polaroid allows unlimited usage of Razor Blade for free while invulnerable, granting a huge damage boost. Very helpful when fighting late game bosses.
- In The Womb and all levels onwards:
- Heart price doubles
- Moreover, if Isaac has just enough Red Hearts for the trading and some spare Soul Hearts, it doesn't utilize those Soul Hearts but uses up all the Red Hearts, thus killing Isaac. A remedy is to always keep a half damaged Red Heart container.
- See also: Scapular's Bugs section
- Using the Razor Blade will count as damage for 'No-Damage-Runs'.
- According to Edmund in this video, using the Razor four times results in double damage for that room.
- As of Wrath of the Lamb: Eternal Edition, the Last-Will Symbol of Razor Blade will be blank if you killed yourself with it.
- After using this item, Isaac looks like a Dople.
- It is most likely a reference to how razor blades are used for suicide or self abuse