I just started on Amitiza Tuesday night after having been on nothing since Zelnorm was pulled off the market. I was very, very backed up and the doc had me drink a bunch of crappy laxatives to get "cleaned out" so by Wednesday night (yes, it took that long) I was pretty much flushed out. It was mostly water coming out. I still haven't had a bowel movement even with the Amitiza but I feel nauseous, bloated, cramping pain, backache, difficulty breathing, etc. How long does this stuff take to work? Do you supposed the "cleaning out" thing is slowing it all down? I have actually been eating, although mainly in the evening as I feel much sicker to my stomach during the day. I am also worried about gaining weight from being on the Amitiza. I have heard stories about that. Can someone shed some light on this?