I've been on Topamax for migraines for a few months now and have experienced decreased appetite and one day I went to drink a soda and it was flat at first and then after a second or two it fizzed in my mouth, you're the first person who mentioned the flat soda, beer does the same thing!!!! I don't care I love the Topamax, I've barely had a migraine since I've been on it and it's made my moods much more relaxed, which has made my husband and kids happy.