I'm on Topamax too-400mg/day for close to a year now. How much have you been bumped to? I'm sure you know the importance of the water cuz of the possible kidney problems. I kinda had a problem one day this summer. I was sweating like a stuck hug cuz I was really working--had a good pain day. I wasn't drinking anything, and am on Lasix (fluid pill) besides--double whammie.

Anyway, late afternoon I started doing the where I had to go potty really bad, but when I got in there, either there was a drop, or nothing--kinda like a bladder infection. I was puzzled, so I thought, well, maybe cuz of the no water thing....

I started drinking like a wild woman. Forcing fluids--all water. It took a few hours, but that's what it was. I learned my lesson. Drink lots of water. I don't know if diet soda qualifies or not, so I'm sticking to water. It might, but I'm not gonna chance it and go through that again!

Just wanted to share my story for your benefit!
Hugs,
LS