The instructions weren't quite clear, so I had to go figure it out on my own. You need to put water under and outside of the medicine cup so that the water touches the bottom of the medicine cup in order for the unit to properly work. Otherwise, there's no mist.
So I bought this so I wouldn't have to wake up people in the middle of the night if I needed to give something inhaling for the kids. This is super quiet with a gentle buzz from the ultrasonic oscillator.