Very helpful information and explanation, Kathleen! I think I understand now.Since this was my first visit to my doc regarding IBS, he probably wanted to start me on something mild to see how it worked. He's also well-known for his opinion that "most issues" that are stress-related will go away on their own without treatment, once the stress eases, which it almost always does. I do not agree with this but that's his opinion.It sounds like the 2 meds work in different ways, so I could take them at the same time if need be.Thanks again!