Antidote - Bloodborne Wiki

Antidote is a stackable, consumable item in Bloodborne. Antidote will remove the buildup and status effect associated with Slow Poison and Rapid Poison once consumed. 

Small medicinal tablets that counteract poison.
Used to treat ashen blood, the baffling sickness that ravaged Old Yharnam long ago.

These tablets only provide short-term relief. The ashen blood ailment eventually triggered the spread of the beastly scourge.

Acquisition 

Antidote can be purchased from Bath Messengers and occasionally found throughout Yharnam.

Usage

The hunter can use this item through the quick access bar or use it by selecting the Antidote in their inventory.

Price

Game start: 300 Blood Echoes
Upon entering Cathedral Ward: 600 Blood Echoes
Upon inspecting the skull of Lawrence and triggering Nightfall: 1,300 Blood Echoes
After defeating Rom, the Vacuous Spider, and triggering the Blood Moon: 2,300 Blood Echoes

Notes 

Maximum held: 10
Maximum stored: 99