Effects - Opioid pharmaceuticals and the GI tract?

[spritz!!spritz!!]

Swim is a pretty frequent opioid user. Probably 3 or 4 times a week he will indulge in hydrocodone (containing apap), tylenol 3s and 4s (codeien and apap), oxycontin, and on occasion tramadol.

Swims question may or may not fit here, but he has an EBG (doc sticks a camera down swims throat to see if there are any ulcers, etc.) scheduled, and was just curious if opioids with or without APAP can cause any damage or abnormalities that could either make opioid use apparent, or create a false positives for gastrointestinal or other stomach problems that would show up on an EBG.

SWIM only VERY rarely gets constipation from opioids, and it hasn't happened in over four months.

thanks for any help!