I was on Zelnorm for about a month, but I did not have IBS. My doctor put me on Zelnorm because for a year, I had been having stomachaches constantly. They were accompanied with gas. Zelnorm worked the best for me out of all the other medications I tried - Tums, Zantac, and Aciphex. I didn't have any side effects with this. I stopped taking it on February 23rd. For the whole month of March I didn't have any stomachaches or hardly any gas.
Hope this helps!