The flask heals the player, cures poison, and applies poison immunity for around 14 minutes. For one hour, it boosts the player's maximum life points cap by +3 per Constitution level, for a maximum of +297 at level 99. This stacks additively with the life point boosts from bonfires, Fortitude, and life point boosting equipment. After being used, the flask is destroyed.
- It is a common misconception that the life point bonus from bonfires and the thermal bath would behave in the same way. While they both give a life point bonus, the boosted amount from the thermal bath only depends on the player's Constitution level, while the bonfire boost is affected by both the Constitution level and the worn equipment.