The black marks left by long acne can not be dealt with in general, after a period of time, the black marks will subside on their own; but if after a long time still can not subside, you can remove it through medication, physical therapy and other ways. 1. Medication: You can use hydroquinone cream and other drugs to treat the black marks left by acne. Hydroquinone has the function of antioxidant, stabilization and reduction, which can prevent the production of pigment, and it also has the function of fading for the existing pigment. 2. Laser treatment: long acne black marks can also choose laser treatment, the laser mainly uses the principle of photothermal, direct action on the epidermis or superficial dermis decomposition of melanin particles, so that the melanin metabolism through the lymphatic discharge, to achieve the purpose of the treatment of black marks, common laser treatment, such as tuning Q laser, picosecond laser, and so on. There are many ways to treat the black marks left by acne, and all of the above ways need to choose regular hospitals and be completed under the guidance of doctors. It is recommended that patients seek medical treatment in a timely manner, not to abuse drugs privately, so as not to lead to adverse consequences.