'It seems there was some rather unusual kind of poison in that snake's fangs that keeps wounds open. They're sure they'll find an antidote, though; they say they've had much worse cases than mine, and in the meantime I just have to keep taking a Blood-Replenishing Potion every hour."
-- Arthur Weasley (OP22)
The Blood-Replenishing Potion is a type of medical magic that replaces lost blood, rather like a blood-transfusion.
References from the canon
- When Arthur Weasley was attacked by Nagini the snake at the Department of Mysteries, he had to take a Blood-Replenishing Potion every hour at St. Mungo's Hostpital until the Healers could find an antidote for the venom of the snake that bit him. Something in that venom was keeping the wound open and he was bleeding whenever they would remove the bandages (OP22)
From the Web
"Blood-Replenishing Potion" from Harry Potter Wiki