That happens due to the obvious side effect of most opiates. It's a secondary nature of those drugs to slow gastric motility. Whenever I hear someone talking about taking any painkillers, I remind them to drink as much water as they can. As far as the fiber issue goes, psyllium husks taken twice a day helps alot of poeple. It's pretty cheap and you can get it just about anywhere. Plenty of green veges and dark berries will also assist in keeping things as close to regular as one can hope for.
If that doesn't help, I would suggest doing a fruit only diet for about 2 days. You may also want to take some probiotics or throw in some yogurt with the fruit to assist with the positive bacteria in the colon. Those aid in a healthy movement as well. A healthy colon is a great thing that most people neglect these days. And yes, sometimes I am guilty of this too. Sometimes nothing feels as great as the feeling after a good healthy poo..
