Topical JAK inhibitors, such as ruxolitinib, significantly improve repigmentation in non-segmental vitiligo by suppressing IFN-γ–JAK–STAT signaling and downstream chemokine production, reducing autoreactive T-cell recruitment to the epidermis.

When skin cells are stressed, they release signals that attract immune cells to attack pigment-producing cells. These immune cells release a chemical that turns on a switch inside skin cells, causing them to produce more signals that pull in even more immune cells. This creates a cycle where pigment cells keep getting destroyed. A medicine applied to the skin blocks that switch, stopping the signal production, preventing immune cells from entering the skin, and allowing pigment cells to survive and make color again.