I'm really happy with my results. I read a lot of reviews and was really scared it would be too painful. I asked to stop as soon as I felt pain. I did 3 treatments and tried to do the fourth knowing the pain was coming and got a substantial jolt and that was it for me.
I did get zingers the rest of the day. It really hurt a lot. I took some AdvilPm and slept for 2 hours. Painful zingers were experienced through the evening but the started to decrease. Slept through the night and all pain is gone. Overall I was prepared for the pain and that made a difference for me. My smile looks awesome now. I will keep up with my whitening so that I don't have to do that again.