I have been taking Asacol for IBS for almost three years on the advice of my doctor. I went to a new doctor who said that the Asacol was not needed and said that I could stop taking it. When I stopped, I was sick for days until I gave up and began taking it again. I don't know why it works for me along with Levsin, but I definitely feel better on it than off it. I wanted to let you know that when I was looking into Asacol this week, I found some info about a generic form of Asacol. I am not sure if it is available in the US or what the deal is but it is called Mesalamine. Just thought you might want to look into it.Kim