Bisacodyl
"Took 2 tablets at 9pm. Rudely awoken at 1am with horrendous nauseating lower abdo cramps. Felt like someone was reaching into me and was tugging on my intestines.  

After more than an hour of misery, writhing around in bed, the pain became so severe that, not knowing what else to do with myself I staggered to the bathroom to sit on the loo.

Pain only got worse, so I curl up into a ball on the bathroom floor. Next thing I know is I'm on my back looking up at the ceiling having passed out. Sweating, shaking and ears ringing I call out to my boyfriend who got me a pillow and blanket and sat with me until I was able to get onto the loo and pass the entire contents of my digestive system. So humiliating.

Was it effective? Yes. Worth it? Hell no!"