I've noticed some pain killers working great for me, while other have no effect.
Works for me
Doesn't work for me
I doubt there is much of a placebo effect at work, since most of these either did or did not work when I first took them, without having expectations either way.
Whenever I have a head ache, I take an APC. I suspect it's actually the aspirin in there that does the job, since when I take just paracetamol, it doesn't do squat. As a kid I got children's aspirin, which worked.
I once had a severe back ache. I was prescribed diclofenac (a larger dose than the over the counter version), which didn't work. I was then prescribed tramadol — same results. I then tried naproxen, which worked rightaway.
Why do some pain killers work for me while others don't?
Is there an underlying mechanism, that explains why some of these work for some people while others don't? Does that predict if pain killers that I haven't had to use yet will work?
Please note that I'm not looking for medical advice on which pain killers to take; I'm just curious about how my body interacts with the various ones.
I have asked this question before, over on the Biology Stack, but I haven't received a satisfying answer yet, just the general observation that different drugs affect different people differently.