Neville said something about looking into Wolfsbane, but he didn't explain it at length, just that it's a potion that's developed later on, and its primary ingredient is a poison. So, brewed incorrectly, side effects can include death.
Sedatives have little to no effect. To take enough to calm the wolf would to a lot more damage to me.
[...] I have friends who calm me down. Come to think of it, you probably know this.