From the Super Mario Wiki
under the effect of the Red Essence
A Red Essence is a drink in a red-colored bottle in Super Mario RPG: Legend of the Seven Stars that, when used in battle, makes the character (Mario, Mallow, Geno, Bowser or Toadstool) invincible for at least three turns. Rarely, a Red Essence will last for up to five turns, and the player may also be able to get a freebie. It also removes all status effects from the recipient. This may come in handy when fighting tough bosses, such as Jinx or Smithy. The Red Essence is available in the Inn in Nimbus Land given by Toad after Mario wakes up from a nightmare, and there is a hidden one in the Forest Maze near the save point. It is also possible to randomly receive one from Grate Guy while playing "Look the Other Way," but it is somewhat rare.
Names in other languages
Reddo Yosshī Ekisu
|Red Yoshi Extract. Also see Yoshi Ade.