Deflating Draught

From UnknowableWiki

A Deflating Draught counteracts swelling; it is unclear whether the potion can be used for natural swelling, such as from an injury, or whether it only works as an antidote to the effects of a Swelling Solution.

Severus Snape distributes a Deflating Draught to each affected member of his second-year Slytherin and Gryffindor Potions class after Gregory Goyle's cauldron of Swelling Solution explodes, due to the Filibuster firework Harry Potter had thrown into the cauldron. The subsequent mayhem provides a distraction which enables Hermione to enter Snape's office to steal an ingredient for the Polyjuice Potion the Trio is brewing (CS11).