... the migraine so I only take it if I'm on the verge of going to the ER. I know they can cause a rebound migraines and I'm constantly trying to figure out if I'm having a rebound or actual migraine. How many days in a row do you have to take fioricet before the rebound thing starts? And then how long to do I have to stay off the fioricet afterwards? I'd try exedrin, but they mess up my already sensitive stomach and they make me a nervous wreck. This is the time of yr the migraines are the most frequent since I live in the midwest where the weather than change in a matter of hours