Bisacodyl
"I'm a medical doctor and all I can say is this is the first time I've taken an irritant laxative and wow. I actually contemplated calling an ambulance when it hit me with intense hypogastric pain which obviously irritated a sacral nerve as my feet started to throb in pain while my bowels viciously spasmed. I should have known better and taken a hyperosmotic like movicol. First attack was 6hrs later followed by another after 2hrs. I thought this is what death must be like. I was out for the day with exhaustion and dehydration and will never take this again. I'd rather have a colleague give me an enema in future. Take with caution."