What effect are you looking for? If you need an rx for nausea, Zofran isn't your best option. I have it in the house for when some is actually v* from a virus, I don't think it's meant to be taken daily for anxiety/upset stomach. Yes, it does cause major headaches and can cause severe constipation, so really I am surprised your doc prescribed it! I would advise going back for something different. It will work should you ever actually feel nauseated do to a sv*, so it's good to have on hand, but for daily use, I would ask for something different.