MiraLax
"I have had very painful Irritable Bowel Syndrome-Constipation for most of my life and have gone as long as three weeks without a bowel movement. It hasn't responded to changes in diet, exercise regimens, or fiber supplements. (In fact, the fiber made it much worse!) Other laxatives either don't work or wring me out for days. My doctor prescribed Miralax in 2008 and I have taken it daily ever since with no problem. I still don't go every day, but when I do go the stool is soft, and the motion is easy and painless. I expect to take Miralax forever, and have no problem doing so. It's a beneficial, versatile medication that's definitely worth a shot if you're battling constipation."