I'm not going to mince words here. I experienced major constipation while on Topamax, but I am not sure, and neither is my doctor, that Topamax caused it. I ended up going off of it because I could not find anything, even prescription med, to make me go to the bathroom. It scared me. Finally found Benefiber, which was great, but not sure if it was the Benefiber or going off the Topamax or a little of both that really worked. But I'm about to go back on Topamax today because of reading on these forums that the side effects eventually go away, and my migraines are getting worse again and lasting longer than a day. Concerning the stomach issues as a side effect of Topamax, you don't read many people having this. If you look at the side effects in the insert, stomach issues are rare but possible. I guess we might be in the rare category. Good luck. Perhaps if you stick with it, the side effects will go away.