Bisacodyl
"I am 5 feet and 135 pounds. I took ONE tablet and had multiple NORMAL BMs over a 24-hour period with no cramping, nausea, or sweats. TIPS: 1) Take with ALOT of water and some food; 2) TAKE ONE at the beginning; 3) DON'T IMMEDIATELY SLEEP; 4) WAIT 24 HOURS BEFORE TAKING MORE."