Magnesium hydroxide
"This stuff is the real deal. It really clears you out. I had my gallbladder removed and was on pain meds, so I was unable to "go" for at least 5 days. I panicked because normally I poop 6-7 times a day. So I called the nurse scared. She suggested milk of magnesia. The bottle called for 2 tablespoons, but I felt so binded and plugged up that I chugged 3 tablespoons. And it began. 20 minutes after I drank it. It was like an explosion of chowder, every 10 minutes. I'm glad it worked, no cramps, no pain, just extreme anal gushing and this happened every 10 minutes making it inconvenient and annoying but hey it had to be done. I got the berry flavored one and it was relatively tasty."