"Just dab it on, that bruise'll be gone within the hour.... We had to find a decent bruise remover. We're testing most of our products on ourselves."
-- Fred Weasley to Hermione (HBP6)
Medical magic: this is a thick yellow paste used to heal bruises.
References from the canon
- The twins gave some to Hermione to treat the bruises caused by their prototype punching telescope (HBP6).