Ginger Snaps: Unleashed (2004)

Brigitte's on the run from Bailey Downs, and she tries to prevent what happened to her sister, Ginger, from happening to her by shooting up with monkshood. Eventually she collapses and the police that find assume the monkshood is an illegal drug, and she is sent to rehab. She is deprived of the only thing that will stop her from turning into a beast and killing everyone and everything in her way. She meets a girl who is quiet and not well-liked, and much like herself, by the name of Ghost that helps her deal with her new problem and to escape the werewolf curse.