Hi Jon,
I was taking Zonegran and Topomax as a combination. For myself I never experienced any issues. As I always tell everyone who changes drugs and takes medication, be careful with what you are taking as you may experience something which I had not. Something which I like to do when starting a new medication is speak with my pharmacist and obtain information from them regarding the medication itself as they have the PDM available to look up medication including other means.
Things that I like to know regarding new medication are important issues such as:
-side effects
-is there any medication I should avoid (cold medication, allergy pills, etc)
-do I need to eat something before taking the medication
-what is the half life on the medication (this helps me time my dosages)
-what epilepsy medications can cause an issue
-how long until the medication is at full level (2 days, 4 days, 1 week)
Hope the above helps you. Best of luck finding something that helps with your migraine issue.
-SueLynn