There are quite a few substances, charms and plants seen in the Harry Potter universe that are analogous to drugs:
The "Euphoria Elixir" mentioned in Half Blood Prince.
- The primary effect is to induce a state of 'inexplicable, irrational happiness'.
Cheered by this thought, Harry skimmed through his copy of Advanced
Potion-Making and found a heavily corrected Half-Blood Prince’s
version of An Elixir to Induce Euphoria, which seemed not only to meet
Slughorn’s instructions, but which might (Harry’s heart leapt as the
thought struck him) put Slughorn into such a good mood that he would
be prepared to hand over that memory if Harry could persuade him to
taste some …
‘Well, now, this looks absolutely wonderful,’ said Slughorn clapping
his hands together an hour and a half later, as he stared down into
the sunshine-yellow contents of Harry’s cauldron. ‘Euphoria, I take
it? And what’s that I smell? Mmmm … you’ve added just a sprig of
peppermint, haven’t you? Unorthodox, but what a stroke of inspiration,
Harry. Of course, that would tend to counterbalance the occasional
side-effects of excessive singing and nose-tweaking … I really don’t
know where you get these brainwaves, my boy … unless –’
The "Cheering Charm" mentioned in Prisoner of Azkaban
- The primary effect is to 'make a person happy' however, when overdone it can create a stupor and fits of hysterical laughter
‘She could’ve done with a Cheering Charm on her, too,’ said Ron, as
the class left for lunch, all grinning broadly – the Cheering Charms
had left them with a feeling of great contentment.
Then, after a hasty lunch, it was straight back upstairs for the
Charms exam. Hermione had been right; Professor Flitwick did indeed
test them on Cheering Charms. Harry slightly overdid his out of nerves
and Ron, who was partnering him, ended up in fits of hysterical
laughter and had to be led away to a quiet room for an hour before he
was ready to perform the Charm himself.
Alihotsy, mentioned in Fantastic Beasts and Where to Find Them
- Mentioned in Fantastic Beasts, Alihotsy (also known as the Hyena tree) is described as a magical tree, the leaves of which can induce hysteria and uncontrollable laughter.
The Glumbumble (northern Europe) is a grey, furry-bodied flying
insect that produces melancholy-inducing treacle, which is used as an
antidote to the hysteria produced by eating Alihotsy leaves.
The Trading Card Game also suggests that the leaves can be brewed into a draught and that drinking it (or inhaling the fumes) will induce the same hysteria...
Billywig Stings, as mentioned in Fantastic Beasts and Where to Find Them
- The primary effect is giddiness and uncontrollable levitation
Those who have been stung by a Billywig suffer giddiness followed by
levitation. Generations of young Australian witches and wizards have
attempted to catch Billywigs and provoke them into stinging in order
to enjoy these side effects
- Its primary effect seems to be to induce uncontrollable laughter