I've been thinking it would be really useful to have a tag that separates real drugs from fantasy ones.

I personally have drugs blacklisted because of personal history and I'm confident I'm not the only one, however drugs that aren't actually real but still meet the drug tag aren't things that I want blacklisted.

That's why I'd like to separate the two with a tag for either real_drugs or fantasy_drugs, and have the types of drugs aliased to that

This is a good idea. I can't stand images where characters are taking PCP, snorting coke, have used syringes lying around, etc.
But if it's a magic pill that makes their breasts larger, that's something I'm very interested in.