I started taking Keflex for a persistent bladder infection last Friday, and I think it's giving me a kind of diarrhea (or at least multiple, very loose BMs). Until recently, I had become pretty regular, with occasional constipation (which I believe also was mecidine-induced)--a great relief after years of coping with IBS. (I give yoga credit for the improvement.) I used to take Imodium for diarrhea when the problem was really bad, but as I was about to take a dose tonight, I noticed that the box said not to take it if you're on antibiotics. Great time to have this come up--the night before Thanksgiving Day! I'll try calling an on-call doctor or advice nurse tomorrow and see if I can reach anybody, but we're going to visit my brother and my 96-year-old father tomorrow for what may very well be his last Thanksgiving Day, and I don't want to spend all my time in the bathroom. Does anybody know of something else that might control the problem without interfering with the antibiotic? --Laura R.M.