Men who develop dark lips should pay special attention to the presence of hypoxia, which is particularly prone to cyanosis caused by lack of oxygen in the end parts of the body, especially those with adequate blood supply. This cyanosis refers to the color change, some of which may appear as purple, and some of which may appear as black in severe cases, easily appearing at the end of the lips or fingers and toes. After hypoxia, besides the end color change, it will also affect the operation of important organs of the body and cause organ disorders. The common causes of hypoxia should be considered: 1. Cardiovascular diseases: such as congenital heart disease or severe coronary heart disease, heart failure will cause hypoxia, especially in patients with heart failure will be more common, most of them have hypoxemia. This condition occurs and is improved by oxygen therapy. If it is severe low pressure, it is necessary to apply non-invasive ventilator or invasive ventilator if necessary; 2. Respiratory system diseases: such as tumors of the respiratory system, severe inflammation, or chronic obstructive pulmonary disease, may lead to severe hypoxia and trigger changes in the color of the lips, or the ends of the fingers and toes.