Hi, what you read about mixing certain antidepressants and triptans is true. I take a tricyclic antidepressant to help prevent my migraines, and several other medications to prevent and abort them. I just started on it and it takes awhile to build up in the system so I don't know how well it is working yet...Unfortunately, I can't help any with the PMDD. Do you only take the topomax one week before your period and then go off it again after your period (I'm sorry I may just be misreading your post)? Take care.