Darkening of the lips can be considered physiologic as well as pathologic factors. Physiologic factors may be hyperpigmentation and environmental changes. Pathologic factors include bronchial dilatation, pulmonary heart disease, impaired digestive function and impaired renal function. 1. Physiological factors: not paying attention to the protection of the lips after the injury will lead to localized pigmentation, the phenomenon of black lips. In addition, a sudden drop in temperature, because of the cold will lead to black lips. 2. Bronchial dilatation: bronchial dilatation will lead to the patient’s lesions in the process of not enough oxygen supply, because the lack of oxygen will lead to black lips. 3. Pulmonary heart disease: because the heart abnormalities lead to lack of oxygen in the human body, there is a black lip color manifestation. 4. Decreased digestive function: at this time, there will be digestive system abnormalities, liver function impairment and other symptoms, may lead to black lips. 5. Impaired kidney function: impaired kidney function also has a certain chance to cause black upper lip color. There are many reasons for black lips, including heart failure, emphysema, pneumonia, etc. In short, black lips are recommended to go to the hospital in time for examination and treatment.