Are you sure it was Altoids. Did you seem them take a full Altoid out of the tin and crush it up?
Coke cutters are looking for stuff to look like coke and snort without any harshness. So whatever real coke is cut with ( as long as its safe ) I would guess thats what they probably use in the movies.
Lactose is the least sweet of all the natural sugars. It is one-seventh as sweet as sucrose. Lactose has virtually no natural taste of its own so its used in applications as a neutral filler.
I’ve been studying lactose for years since I found I was lactose intolerant myself and I’ve never heard of anyone reacting to the taste of lactose or throwing up because of its presence.
Are you sure you’re not reacting to one of the other fillers?
I saw white powder, I saw an open, partially empty Altoids container, and other people were watching it. (I mostly had my back turned, but I did see some of it.)
Maybe lactose mixed with cornstarch but what makes me gag is that very very subtle sweetness. I also can’t drink tea that’s been sweetened but just a bit, I have same effect.