How long is it safe and effective to use Zofran? Your website says not to use Zofran more often or for a longer period of time than indicated. I can't find anywhere the maximum amount of time it's OK to take this. I take usually 1 or 2 per day when I feel the nausea coming on and have for many months now ... through chemo, surgery, and now with arimadex. I think it's the only thing keeping me from feeling very ill!