Fairies' Tears

Fairies' Tears is a kind of health potion found in The Legend of Zelda: Twilight Princess. It is only available after Link has completed the Cave of Ordeals. On the fiftieth level, the Great Fairy will present him with a bottle of Tears, which will restore his health to full whenever he drinks it. From that point onward, the bottle can be refilled at any of the spirit springs in Hyrule.

It should be noted that, as the Cave of Ordeals is optional, Fairies' Tears are not required for the completion of the game.