I tried Topamax but couldn't tolerate it. Unfortunately, I don't remember what side effect was so bad. I think it was making my pain worse. I'm a chronic pain patient, taking Neurontin successfully, except it makes my legs and feet swell horribly. So trying alternatives. I think it was just that it made my pain worse, instead of better.
Regarding the weight loss, I would say it is still worth a try. Side effects are SO individualized, at least that one is. You just never really know unless you try it. Constip, sleepiness, that kind of thing, yes is very common. But weight loss just is not that common.
Good luck, whatever you decide!
Moderator for Chronic Pain forums and
Chronic Fatigue Syndrome forums