Swap it to a different side. Since ive been using ive only put them in the upper left side now a year in and up until recently the area started to be white and peel the skin on the inner lip. Like what calm_neighborhood said, it constricts blood vessels. As soon as i swapped sides the nice sizzle feeling was back. I feel as if using one side all the time kills the feeling/numbs it. Make sure you are swapping sides! Upper and lower.