When you guys say Phospho soda, do you mean magnesium citrate? At least that's what I think I mean, and what I think you mean. HAHA Follow that one!When I had to have an IVP done for frequent UTI's, they gave me that stuff to drink 12 hours before. I HAD NO CLUE WHAT IT WAS GOING TO DO! But I think that it would/should do the trick in helping someone empty their bowels. I know mine sure emptied out. During an IVP, you lay on an xray table while they take repeated xrays over like an hours time to follow an injected dye through your system. I was squeezing my poor little cheeks together the whole time. That stuff turned everything in me into pure liquid. The total effects took days to go away. I told my Mom it was like urinating from the wrong hole. The cramps weren't that bad though, very minor.As for enemas, I had to do 2 of those a few hours before a flexibal sygmoidoscopy. I was so nervous. It worked within an hour. I don't remember much cramping at all. And I didn't have much food in me, so not much had to be removed. I would certainly say try the phospho soda. And seek medical help if it's been 4 weeks since you've had a good BM. That can be a signal of a problem that may not even be related to IBS.Liz