The first time I took FLagyl was about 5 years ago, after having a tooth extracted. Then I started having diarrhea. I had numerous tests that told me nothing, so finally, I went to see a gastrointestinal consultant and he told me it was the Flagyl, and can leave a certain % of patients like this for 3 months. Yes, it stopped after 3 months.
Early last year I was prescribed Flagyl again, after contracting a waterborne amoeba... and I was again left with diarrhea for 3 months.