Found in a small container, this powder resembles Dust of Disappearance, and Identify reveals it to be such. There is enough of it for one use.
As a Utilize action, you can throw the dust into the air, forcing yourself and every creature in a 30- foot Emanation originating from you to make a DC 15 Constitution saving throw. Constructs, Elementals, Oozes, Plants, and Undead succeed on the save automatically.

On a failed save, a creature begins sneezing uncontrollably; it has the Incapacitated condition and is suffocating. The creature repeats the save at the end of each of its turns, ending the effect on itself on a success. The effect also ends on any creature targeted by a Lesser Restoration spell.