Hey girl! It's a really common drug...
You're likely to experience some of the common side effects (nausea, tingling fingertips/toes, loss of appetite, headache, etc.) within the first little while while your body is adjusting to the new drug.
The serious side effects are very rare & usually only happen when you're on another drug that reacts w/ the Topomax, but if your Dr knows all the drugs you take (and your family history) he will not prescribe a drug that reacts negatively.
Good luck