I think opioids are more likely to give you constipation that not. I had over a year of that while on morphine (I've taken it in the liquid oramorph and 12hr release zomorph capsule forms). More recently, mum tried some opioid weekly release patches for pain relief. Her GP prescribed Cosmocol(macrogol) at the same time. Mum needed it.

Addiction seems to be another problem with this group of drugs. I may have been lucky on that. I was able to get myself off the remaing zomorph without withdrawal problems.