If I remember the t.v. commercials for those products, diarrhea is a side affect. And no, you wouldn't necessarily get it right off the bat, because those kinds of drugs, I believe, build up in your system, so it may take a while before you develop a reaction to them. You need to call your dr's office and tell them you have developed intermittent diarrhea and you suspect your medication and what is to be done about it? Sometimes people with IBS are put on those medicines to make their diarrhea better, but it's always possible that it can make it worse or cause it in people who didn't have it before.