Drugs to see through the Illusion? No problemo, just make up a new drug or claim that an already existing drug has the properties you are looking for.
You could claim that any hallicunogenic drug actually "removes" the illusion that is our second set of eyelids (eg. something similar to LSD actually shows your players what is REALLY there, instead of another set of illusion).
I believe there was a drug in the campaign called "Judas Grail" that did just that... I think they called it Crimson Death or something like that - maybe you should look into that if you have access to the Judas Grail.
In an old campaign I ran, Ne Plus Ultra, there were a group of junkies who spent all their day looking through the illusion as a form of entertainment.