The Virus is a passive item.


  • Inflicts poison on enemies who make contact with Isaac.
    • Dlc na indicator.png The poison deals 2 damage per tick (3 damage per second) and lasts for 2-3 ticks.
    • Dlc ana† indicator.png The poison deals Isaac's damage per tick (1.5x Isaac's damage per second) and lasts for 2-3 ticks.
    • Dlc a†nr indicator.png The poison deals Isaac's damage per tick (1.5x Isaac's damage per second) and lasts for 6 ticks for normal enemies and 3 ticks for bosses.
    • Dlc r indicator.png The poison lasts for 6-7 ticks and deals damage equal to (0.2*HeartContainers^2) + 2, where HeartContainers is the total number of heart containers and bone hearts Isaac has.
      • The poison can be continuously applied to bosses, which normally are immune to status effects for a brief time after being inflicted with one.
  • Dlc r indicator.png Lets Isaac deal 24 contact damage per tick on top of applying poison (48 damage per second).
  • Dlc anr indicator.png Enemies who are killed after they have been inflicted with this type of poison have a 20% chance to drop Black Hearts.
  • Dlc nr indicator.png -0.1 speed down.
    • Dlc na indicator.png This is not applied until the next time Isaac's speed stat is updated.
  • Dlc r indicator.png +0.2 speed up.
  • Dlc a indicator.png This item belongs to the Spun set. Collecting three items from this set will transform Isaac into a buff berserker.


  • Dlc anr indicator.png The black heart is only dropped if the poison was caused by The Virus. The item's effect doesn't extend to poison tears.
  • Dlc anr indicator.png If an enemy doesn't do contact damage, The Virus can safely be applied to it for more chances at black hearts. Black flies, Mulligans, and Hosts are the most common enemies this can be applied to.
    • Dlc anr indicator.png With Collectible Skatole icon.png Skatole, Hives and Swarmers will constantly spawn normal Flies, meaning they can be endless sources of Black Hearts.
    • Dlc na† indicator.png Although Stonies and Shopkeepers can't be visibly poisoned, they still can drop Black Hearts if destroyed after being touched.
  • Enemies won't start taking poison damage if they are pushing up against Isaac; The Virus will be constantly trying to apply poison and refreshing the ticks where poison damage would occur.
    • Dlc anr indicator.png Collectible Gnawed Leaf icon.png Gnawed Leaf and The Virus can still work if Isaac has a short-range orbital such as Collectible Cube of Meat icon.png Cube of Meat or Collectible Ball of Bandages icon.png Ball of Bandages, as it will kill enemies pushing against Isaac that are not taking poison damage while still dropping Black Hearts.



  • Dlc nr indicator.png Collectible Odd Mushroom (Large) icon.png Odd Mushroom: The speed down from the Virus does not stack with the Odd Mushroom; if both are collected, only a total of -0.1 applies.

In-game Footage

Unlockable Achievements


  • Upon picking up The Virus, Isaac looks very similar to Lust, which is fitting since Lust also drops The Virus.
    • As such, The Virus may be a reference to an STI.


PC 26ND Z11A (Treasure Room adjacent to spawn)

PC 1389 DNH1 (Treasure Room adjacent to spawn)

PC Dlc a† indicator.png BothIndicator.png FKVG 36FZ (Lust fight right of spawn)

PC Dlc r indicator.png A643 V2FE (Treasure Room adjacent to spawn)

PS4 913D J63B (First floor Treasure Room)

3DS TKYD 8DRA (Treasure Room adjacent to spawn)

Switch Greedier Mode Indicator.png FEKK E8JS (First Golden Treasure Room)

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