Bisacodyl
"I too experienced the hell that other reviews spoke of , severe cramping , dry heaving , light headedness I had to open the bathroom door so my husband could find me if I fainted..this drug is terrible and should be taken off the shelves or they need to revise their side effects.  I kicked heroin cold turkey at home 2 years ago and I SWEAR this little red devil gave me deja vu I had the exact same symptoms. Absolutely nothing gentle about it"