Until I took oxycodone one day. I don't remember the reason... perhaps a toothache... but my wife had them at the time (for pain) and I took half a pill. (Not sure about the dosage.) Suddenly, euphoria! That was a really strange sensation, considering I had not been feeling good in... years, probably, except for the (very) rare mood swing that went "up" instead of "down".
Of course, the next time you take it, it doesn't work as well, so you take a little more. The usual addiction cycle. Except that didn't happen in my case; a higher dose (say, a whole pill) would not make me feel good; it would just make me feel weird and nauseous and dizzy. So I would wait a day or two, then take the half pill again. This went on for a little while without any bad side effects (that I am aware of).
(At some point my wife stopped taking it, and so I had to do the same. I don't think there was much of a withdrawal, probably because of the low dose.)
I think oxycodone might actually be helpful for me, as an antidepressant. Feeling better every three or four days is not a cure, but it sure beats feeling miserable all the time. There is even some evidence that for some people with non-addictive personalities, it might be beneficial. [1] But, needless to say, I am very reluctant to bring this up to doctors or counselors, and even if I did, they probably could not, or would not, prescribe it anyway.
It's frustrating though, to know that there is a medicine out there that at least does something against my depression, yet I am unable to get it.
[1] https://ajp.psychiatryonline.org/doi/full/10.1176/ajp.156.12...