Lizzie, this has been one of my worst issues post op. I was never very regular to begin with and used a senna tablet twice every day before my surgery. I now use the fiber choice chewables and they taste pretty good. Milk of Magnesia is vile and I could not drink enough to make a significant difference. When things get really bad, which is at least once a week for me, I use glycerine suppositories. They work fast, about 30 to 60 minutes, and soften stool enough to pass. The problem with fiber and laxatives is that they do not necessarily soften stool, which can be really nasty and painful as the laxative kicks in but the stool is still blocked. The glycerine suppositories take care of that but making the stool soften and pass relatively easily. It is not the most comfortable thing to go through, but for me it is the only thing that really works. Good luck!