Hi dear , The condition you mention in query is clearly indicating a condition known as hyperpigmentation . This occur when melanin producing cell start producing excess pigment , There can be many trigger factor like excess sun exposure , hormonal changes and side effect of any medicine . I would suggest you to give cold compresses to lip twice a days , apply kojivit cream after washing face twice a day and apply lip balm containing broad spectrum sunscreen whenever going outside . If condition doesn t improve in a month the consult dermatologist again . Doctor may recommend procedure like chemical peeling and laser therapy . Hope your concern has been resolved. Best Wishes, Dr. Harry Maheshwari