Binding of Isaac: Rebirth Wiki

Added in Afterbirth †

Contagion is a passive item added in The Binding of Isaac: Afterbirth †.


  • In each room, the first enemy killed will release a gas explosion and poison nearby enemies.
    • Poisoned enemies will also release gas upon death, spreading the effect.
      • Poisoned enemies do not need to die while the poison is still active to spread the effect.
    • The effect will also activate if a Shopkeeper Shopkeeper is destroyed before killing any enemies.
      • Re-entering a room and destroying another Shopkeeper Shopkeeper inside it will trigger the effect for a second time.


  • The initial gas explosion deals 5 damage, and the poison deals Isaac's tear damage per tick, for 6 ticks.
  • The gas explosion and poison can damage friendly enemies.


  • Added in RepentanceGigante Bean Gigante Bean: Greatly increases the size of the gas explosions, making the poison spread much more effective.


  • Dr. Fetus Dr. Fetus: Bomb damage does not apply to poison damage.
  • Epic Fetus Epic Fetus: Missile damage does not apply to poison damage.
  • Ipecac Ipecac: Ipecac only applies a 2x multiplier as opposed to +40 to poison damage.
  • Poison tears: No effect. Gas explosions will only be triggered by poison caused by Contagion
  • Second Hand Second Hand: Poison duration is not affected.

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