http://fallout.wikia.com/wiki/Third_Street_Municipal_Building_terminal_entries

There's an entry that mentions LSD. We don't see it 200 years later, so was the formula lost?

LSD or 'acid' is a powerful hallucinogenic drug.

Not sure it's in the game

I'm a little bit confused

From what I've read on the Wiki, it think it was too difficult to produce. IRL LSD comes from ergot, a fungus that grows on rye. Apparently there was a character in Fallout 2 that got in depth into it:

Plus, who needs LSD when you got sacred Datura?