I actually left urine on my face for a whole entire night once. I didn't get much sleep at all because of the smell =/ bleh. I didn't notice much of a change in the morning, though. But I have been dabbing urine all over my face twice a day for the past 4 days now, and I must say that my face DOES look better. It seems that old blemishes are clearing up and no new ones are forming. But, I have been drinking urine too, so I don't know which one exactly is doing it for me. Maybe the combo of both! Hehe.