I think so, yes. Always OK. Is it always the best possible way to go? Probably not.

And no, I don’t think it matters if it’s physical or mental, what matters is balancing the risk of the drug vs. the benefit. So for example my kid takes Adderall for ADD, I don’t, because I know how much I like speed and also have a (very far past) history of disordered eating and still occasional anxiety about eating - I judge the potential risk too high even if it would “fix” my mind in one way, and make me better in that way.

But yeah, if it will improve you overall why wouldn’t it be ok?