acanthosisnigricansazelaicacidchemicalexfoliationglycolicacidirritationIngrownHairsmandelicacidsensitiveskincareunderarmhyperpigmentation 12 Sep 2026 Dark Underarms After Two Months: What May Explain the Change and How to Avoid Irritation Visible improvement in dark underarms can occur when repeated irritation, friction, shaving damag…