You can either buy another one of those potions (i.e. burn salve fortitude tonic) or you can use GG's cleansing boon. Other than that they are unremovable, so I suggest you just try to avoid them completely.
I always just save those enemies till I am a higher level and then one shot them without incurring weakening or corrosion as they are very bad. (weakening especially)
We made an expansion and it is awesome. Really, you should check it out, especially if you're looking for some extra challenge.
Download over at ddmod.weebly.com!