Magnesium citrate
"I've suffered from IBS-C for a few years now. Normally Miralax does the trick but can take a few days. I decided to try MC, drank the full 10oz of the grape flavor thinking I had to. Should have stopped at 1/3 of the bottle. Any who, drank it from 7:45-9:30pm after puting it in the freezer for 30 minutes. Didn't feel much right away and thought it didn't work. That's until my stomach started gurgling. Then came the pains and a lot of bloating. Holy batman, the pains! Still nothing came out after an hour filled with multiple tries. Laid down hoping to sleep through the discomfort. Was awaken at 4am and sprinted to the bathroom. It worked. It's still working 8 hours later! Solution is VERY effective, may take a few hours to kick in."