Oh yeah...the pain meds. Since I'm sure you're not a delicate flower of the Victorian age and you won't get the vapors from the mere mention, I'm sure I can say this.
They will cause constipation and can back you up something terrible. Our docs recommended upping fiber intake, upping water/fluid intake and a stool softener as opposed to a stimulant laxative, to help keep things moving as they should.