I have no direct experience with either of these types of meds, but I've experienced a lot of weight gain from a tricyclic antidepressant. Those change your metabolism, not your appetite, so you gain weight while eating the same amount.
Unfortunately, exercise didn't help me - it's true generally for women that we can't lose fat from exercise alone. Dieting helped to a point, but I had to restrict my calories so severely it was affecting my ability to concentrate.
I didn't lose the weight for good until I got off the med (and then, it came off not only without trying, but without my even being aware of it until I'd already dropped 7# and someone else pointed it out).
Can you ask your doctor to try something else? Or have you already exhausted most of your options?
Speed comes from what you put behind you. - Judi Ketteler