I take miralax daily. I also had the same ... One movement of very loose/diarrhea per day sometimes. But because I have IBS it's hard to predict when those days will be. Sometimes that happens when I have a cold or virus too. Or if I ate something that disagrees with me. When I'm on an antibiotic that I know produces diarrhea, I sometimes cut my miralax in half or even a quarter. Miralax is only a stool softener, so it pulls water into your colon to soften up your stool. That's literally all it does, and it is so helpful for those of us who are chronically constipated.