The Acid Bottle is a white chemical jug of acid found discarded in Grand Bulim Avenue train station. Unlike most other items, when picked up, the acid bottle is not committed to the inventory, but rather held in the player's hands. While holding the bottle, the player's speed is reduced and they are unable to open doors or use weapons. Walking onto a puddle in the main room will cause the player to slip, and the acid bottle will spill onto the player, killing them. When returning to this room, a bloody goop can be found where the player slipped, mirror enemies will begin spawning, and the door leading onward will be unlocked. Interacting with the goop will cause a prompt to appear onscreen displaying various negative comments.
- Dying from the acid bottle is required to proceed through the area.
- A spitter can be seen drinking from the acid bottle during a late-game cutscene.