The first week, pretty much the entire time. But I felt improvement right away. They were healing, not riping more and bleeding. First thing in the morning and before bed and after eating. I also had some set backcs from oranges, lemons and cayenne pepper. Make sure to rinse the mouth and lips well after eating them.
By the end of the first week my lips weren't swollen anymore and appeared normal, but still peeling. My week two the peeling was almost gone. Now I just use it when they feel dry. But being female, I keep lip gloss on during the day, so that might help.
It really didn't take long to heal, surprisingly. For how long my daughter and I had the problem and everything we tried, it work well.