In Shrek 2, what potion transforms Shrek and Donkey into human and horse forms?

In Shrek 2, the potion that transforms Shrek and Donkey is called the Happily Ever After potion.

Shrek drinks the potion while searching for a way to improve his relationship with Princess Fiona. Its effect changes Shrek into a human and Donkey into a white horse. Fiona also becomes human, connecting the transformation to the film’s fairy-tale ideas about beauty and happiness.

The potion is sold by the Fairy Godmother, who wants Fiona to marry her son, Prince Charming. The label’s promise of a perfect ending reflects the character’s plan to replace Shrek with Charming rather than simply offering harmless magic.

The transformation is temporary unless the drinker receives a kiss before midnight. Shrek 2 uses the time limit as a comic plot device while also questioning the idea that a royal or human appearance automatically makes someone happier.