That happened to a good friend of mine back in high school.
We were at a teen dance and afterwards a shit tonne of people went out to a field to drink. Allegedly someone had added alot of acid to his beer(unknowingly) and an 1 hour or so later he was just gone(I assumed home).
I didnt hear from him for months and he never did come back to school for well over a year.
I asked his cousin about him and he told me the story. He ended up hiding in his parents basement for a couple of months and wouldnt leave until they forced him into a psych ward.
Thankfully he bounced back and is somewhat normal now but he has severe PTSD and if that flares up ya gotta get the hell away from him as he gets violent.
Anyways, he told me the story and said it felt like weeks would pass of closed eye visuals and when they went away, he couldnt see colours at all. Also, to this day he cannot taste food. He has the weirdest diet ever now because he knows he has to eat, but has zero taste.
He will never leave an unattended drink anywhere now and still talks about how devastating the experience was some 25 years later.
Fuckin terrifying