In the movies and tv one often sees a junkie or other drug abuser snorting a line or two of cocaine.
Obviously, its not real coke they’re snorting, so what is it? Talc? Confectioner’s sugar?
this site gives an answer, but it’s a “This is what I’ve been told.” kind of thing.
Back in film school I heard they use lactose.
Lactose (milk sugar) is fluffy, white and dissolves into nothing on the mucus membranes. It can be bought in capsules in health food stores and you see it in drug paraphenalia stores (folks cut cocaine and heroin and whatever with it).