I'd be a bit more leery if it was 'Hey, an oxy, let's PARTY!" (wow, that doesn't even sound remotely fun) or "Crap, turned my ankle. There's some oxy in the medicine cabinet left over from when Hubby had his surgery. That might hold me until morning."
TBPO, I wouldn't even think twice about taking a pain pill in that circumstance. It's not my drug, I pretty much always hated opiates, but they do kill pain.
It would be a different story if I were a recovering junkie.