Try not to use too much shimmery luster dust. Some luster dust is marked as edible, and some are marked as non toxic.
I try not use more than 1/4 tsp per cup of liqueuror spirit (vodka, tequila or gin). Just enough to give it a shimmer and light swirls. If needed I might add just a pinch more to a drinkafter I've made it.
Adding a teaspoon or more of the luster dust PER DRINK is not advised, so only add just enough to create swirls in a CLEAR cocktail (which will show the best results).