That one never did much for me, but many people find it effective. I had good luck with Bentyl, but now I am pretty much medication free and control it with diet and stress management. Took me about 30 years though. ;-)
Remember to drink a lot of fluids, as you can get severely dehydrated from this. You also need to make sure you take a multivitamin and possibly other supplements as often you will not absorb the nutrients from the food you eat because they pass through too quickly.
Here's a site I highly recommend, its called Remedy Find. They post patient's ratings and personal stories about treatments and they have great links. This is their IBS page:
http://remedyfind.com/hc_IrritableBowel.aspOne thing you'll have to get used to, locating a bathroom first thing everywhere you go. Thirty one years after my first attack and its still the first thing I do where ever I go. :-)