Long story short
Today, in a homebrew campaign that I DM, a player tried out a natural drug that he found and heard about: Flashberries. In my world it's believed to be a psychedelic drug and those who use it, become delusional: they claim to "see magic" and some say they can even interact with it. The use of arcane arts is commonly believed to not exist at all, while in actuality, arcane magic is very real (but successfully propagated against). When you consume a berry you actually are able to see the weave very clearly, and possibly even interact with it.
The party and a select few NPCs are aware of the reality of magic's existence. So after today's events, it's looking like Flashberries will play a big role in my campaign.
Does D&D 5e cover any consumables that function as addictive (psychedelic) drugs? If so, does it mention positive and negative effects?
If addictive drugs already exist in any of the books I could use (some of) the mechanics as inspiration while homebrewing these Flashberries. For now I'm only interested in what the books already have to offer.