I suffered a pretty horrible Smith's fracture on my dorsal radius two years ago, such that the resident at the ER called his attending, who called the ortho specialist and immediately got 30mg oxycodone's 4x daily just as a stop-gap until they could block in a surgeon skilled enough to work on the Smith's fracture. Even through the egregious pain, I could see a: how those without opiate dependencies can find it euphoric and b: how easily an average person could form a habit without noticing it by escalating consumption.
I've used oxycodone for pain, and have occasionally played with higher dosages. I don't find the effects euphoric. More like numbness, but in a vaguely pleasant way. Or at least, not euphoric in the sense that Psilocybe are. But maybe that's just me. I've never had problems with opiate dependence.
It nukes emotion.