constipation
"Works like a charm - a crampy, semi-painful charm but still I'm 150lbs, 5'7''. 
I would recommend starting with one pill, no dairy before or after, and lots of water to go with it. The pain - and there is pain - is bearable, and if you absolutely need to go, Dulcolax will get you there overnight. But make sure you can afford to be up during a couple hours that night."