hi fionaw, I used the zofran during my pregnancy last year, they gave me the initial dose in hospital after being put on a drip for rehydration.
I was told its safe to use and yep its the one they give to cancer patients.
It was fantastic, I could not have functoned without it and I had ms up until about 22-24 wks I feel your pain!
it is very expensive, but if you can get a script for the higher dose in a larger pack ( I think its the 10mg in a box of 8, ) I used this and just took half a tablet (well wafer, they dissolve on your tongue!) when I really needed it.
I think you will pay anywhere between 40-$75.
i hope you will be feeling better soon.
oh yeah, and I second the hydralyte, fantastic stuff!