Darkening on both sides of the cheeks may be caused by melasma and skin melanosis, which can be improved by topical medication, oral medication and physical therapy. 1. Melasma: Hereditary factors, long-term sun exposure and changes in sex hormone levels may cause melasma, which manifests itself as yellowish-brown pigmentation spots on the face, symmetrically distributed, thus causing the phenomenon of darkening of both sides of the cheeks. This kind of patients first need to strengthen the sun protection measures to help isolate the stimulation of ultraviolet rays on the facial skin, and then can be used externally with azelaic acid, tyrosinase inhibitor ointment (such as hydroquinone cream, tretinoin cream, arbutin, etc.) for localized application to help remove localized melanin deposits, or feasible laser treatment such as intense pulsed light, picoseconds, etc. to help improve the symptoms. 2. Melanosis: Melanosis is a kind of diffuse hyperpigmentation skin disease that occurs in the exposed parts of the face, mainly manifested as gray-brown or black-brown reticular or dotted plaques on the face, which can cause the phenomenon of blackness on both sides of the cheeks. In the treatment of such patients, it is recommended to avoid exposure to the sun, avoid contact with photosensitive substances, topical drugs can be used vitamin E ointment, hydroquinone cream and other drugs for local application, the more serious symptoms can be orally or intravenously injected vitamin C to help treatment. In summary, it is recommended that patients with black cheeks go to the hospital to clarify the cause of the disease, timely treatment, so as to avoid further development of the disease; and it should be noted that the above treatment should be carried out under the guidance of a physician, to avoid the occurrence of adverse reactions.