Peppermint is a mint plant. Severus Snape discovered that adding a sprig of it to the Elixir to Induce Euphoria counteracted the potion's side effects of unrestrained singing and nose-tweaking while he was still a student at Hogwarts in the 1970s. In 1997, Harry Potter had to make an Elixir for Potions, and so he followed the modified brewing instructions that Snape had written in his copy of Advanced Potion-Making as a teen. Professor Slughorn thought the addition of peppermint to the recipe was "unorthodox" but a "stroke of inspiration." It is also commonly used in both the Wizard and Muggle world to flavour sweets and concoctions. It is a known flavour of Bertie Bott's Every Flavour Beans.