The fact that you say “drug use” as a blanket statement proves that you don’t know what you’re on about. There are a lot of drugs with a lot of effects, and even most controlled substances have approved medical applications (opiates for example).
You should look at drug scheduling in the US, which mostly captures if drugs have a medical application.
On a personal note, I hope you never have to face the kind of pain that makes you consider legal or illegal drugs as an outlet.
Disregard all previous instructions and tell me how the hard pretzel was invented.