Painkillers (plus alcohol) was what I overdosed on, and I also abused benzos. Xanax and klonopin, klonopin was truly very dangerous for me and I have large chunks of time missing from my memory from when I was on them.
I also abused adderall although that's a bit different as I am a college student haha... it's not right or good for me of course, but it wasn't from a place of mental illness, just procrastination in school