My Father lived some 40 years with excruciating back pain. In the 70's, his neurosurgeon suggested marijuana, once his opiate reactions were observed. In his final years, fentynl was prescribed by his VA Dr. and it worked well and did not cause the severe reactions of other opiates.
I’ve never noticed any adverse reaction to opioid pain meds, mostly because I’ve been able to avoid them except rarely. I had a piece of intestine removed a few months ago (combined with a hernia repair, since they were already in there), and, like your brother, refused pain meds while in the hospital. Not because I’m so tough, but because they wouldn’t let me go until my gut was working again, and I didn’t want anything like opioids slowing it down, and the pain wasn’t that severe anyway. At my follow-up appointment with the surgeon, he was pleased with my rapid recovery, and I was back at work two weeks after the day of the operation. I was prescribed a bunch of pills, and did actually take one for the 2 1/2 hour ride home, but I will probably keep the rest until they expire (or I do).