constipation
"I have battled constipation for most of my life and for the past 8 years have been on pain meds, which worsened matters.
Bisocodyl is often the only thing that works for me. Yes, the pain can be horrid: sweats, nausea, incredible cramping; I have even hallucinated from the pain. But sometimes you just have to pull out the big guns. 
Something I have noticed, and this might help with some of the issues mentioned here, is that when I don't really need to use it but do anyway, I too get diarrhea and 'immediate elimination' as soon as I eat or drink."