Leech juice

A bottle with some leech juice.

Leech juice is, most likely, liquefied Leeches. It's a purple liquid and it's used in potion-making: in the Shrinking Solution and Polyjuice Potion a dash of leech juice is one of the ingredients (adding too much, however, causes the potion to turn orange instead of the bright acid green it's supposed to be; this can prove disastrous, as making errors in the potion can cause the mixture to become poisonous).

Appearances

• Harry Potter and the Prisoner of Azkaban (First appearance)
• Harry Potter and the Prisoner of Azkaban (video game)
• The Road to Hogwarts Sweepstakes