Normal people with pink lips, in a state of hypoxia may be dark red black, on the cause of oxygen inhalation, taking antidote drugs, treatment of cardiovascular disease. 1. Hypoxia. Normal people if the plateau area or accidental asphyxia breathing can cause hypoxia, carbon dioxide concentration in the blood increased lips can be black, the need for oxygen, or immediately open the airway to maintain smooth breathing. 2. Poisoning. For poisoned people harmful substances will inhibit the ability of red blood cells to bind oxygen produced by the lips black, need to keep breathing usually oxygen, take laxatives or immediately wash the stomach. 3. Cardiovascular disease. Black lips can also be caused by cardiovascular system disease caused by insufficient oxygen supply, need to take warfarin or surgical treatment of cardiovascular disease. Black lips need to go to the hospital to check the cause of the targeted treatment, the use of medication must follow the doctor’s instructions.