The darkening of the face is not necessarily due to disease, and is mostly considered to be caused by physiological factors such as sun exposure, but there is also the possibility of suffering from diseases such as acanthosis nigricans, melioidosis and hepatitis. 1. Physiological factors: If the skin is exposed to sunlight for a long time, the facial skin is exposed to ultraviolet rays for a long time, which may trigger the darkening of the face. 2. Acanthosis nigricans: the cause of acanthosis nigricans may be related to heredity, obesity, and diabetes, etc. Patients will have symptoms such as deepening of skin color, dryness, roughness, etc., and some of the patients may have darkened face. 3. Melanosis: the cause of melanosis may be caused by drugs, constipation and exposure to photosensitive substances, patients will have gray-purple pigmented skin spots, and some patients may have a black and dark face. 4. Hepatitis: the cause of hepatitis may be related to bacteria, viruses, parasites, and alcohol, etc. Patients will experience weakness, nausea, and facial darkness and lack of luster. There is no single disease that causes darkening of the face. After excluding physiological factors, it is recommended that the patient consult a doctor for examination to clarify the cause of the disease.