Potions must be brewed carefully to achieve the proper effects. In certain cases, those are brewed incorrectly or in a dirty cauldron can become poisons.[6][7] In other cases, even potions that have been brewed correctly may in some cases have deleterious effects, even if their intended effect is beneficial; for example, Felix Felicis causes recklessness and overconfidence when used more than sparingly,[8] while the Elixir to Induce Euphoria has side-effects such as excessive singing and nose-tweaking, though these can be countered by adding peppermint.[9]