I tried Milk of Magnesia and had a combination of diarrhea (happened somewhat quickly) and constipation. Really miserable experience! When I talked to my surgeon, he recommended Miralax instead. I took 1/2 the amount recommended to see how I'd respond. Nothing happened, including cramps, which is a good thing) and then a few hours later had the other 1/2. Still waiting, but not feeling bad.