I have suffered with IBS - D for 2 years and have tried everything. I couldn't leave my apartment without at least 8 pepto in my purse. I tried probiotics at the suggestion of another sufferer and it works!!! It took about 2 weeks but I haven't had an episode in over 2 months. There are many different supplements out there -the one i have been taking is called PB 8 ("nutrition now" makes it). Stonyfield yogurt also contains the same bacteria (acidiphilus) so I also eat that for breakfast. It has changed my life. Go to http://www.usprobiotics.org