Leech Juice

• Type: Potion Ingredient
• Source: Apothecary, Hogwarts Potions Classroom stores
• Origin: Squeezed from Leeches

Leech juice is the liquid extracted from Leeches, which are small, worm-like, bloodsucking creatures. The leeches themselves are described as “fat” when handled by Professor Slughorn. They are sold commercially at the Apothecary in Diagon Alley, where they are kept in a barrel and sold by the scoop. The process of extraction involves squeezing the creatures to release their juices, which are then added to cauldrons during potion-making.

Leech juice is a common and essential ingredient in a number of potions. Its most notable use is in the creation of the highly complex and powerful Polyjuice Potion, a brew that allows a drinker to assume the physical appearance of another person. The recipe for Polyjuice Potion requires leeches alongside lacewing flies, powdered Bicorn horn, knotgrass, fluxweed, and shredded Boomslang skin. The fact that leeches are sold cheaply and openly in Diagon Alley (for two Knuts a scoop) and are part of the standard Hogwarts Potions stores suggests they are a fundamental ingredient used in a variety of other, likely less complex, potions taught to students.

Leech juice, via its source, features at several points in the narrative, primarily in the context of brewing the Polyjuice Potion. In their second year, Hermione Granger, Harry Potter, and Ron Weasley required leeches for the Polyjuice Potion they brewed to investigate Draco Malfoy. As it was not an ingredient readily available to second-year students, Hermione had to steal them from Professor Snape's private stores in the dungeons. The successful brewing of this potion allowed Harry and Ron to disguise themselves as Vincent Crabbe and Gregory Goyle and enter the Slytherin common room. In the summer before their fourth year, Harry, Ron, and Hermione observed a barrel of Leeches for sale at the Apothecary in Diagon Alley, confirming their status as a standard, commercially available potion ingredient. During Harry's sixth year, Professor Horace Slughorn was seen squeezing the juice out of a bundle of fat Leeches directly into a student's cauldron during a Potions lesson, demonstrating a hands-on and practical application of the ingredient in a classroom setting.