What is the reason for a black mouth?

Lips black, common reasons are: 1, digestive system diseases. Such as diarrhea or constipation, loss of appetite. Some people lips will show a lot of black spots, may be multiple polyps of the intestinal tract. 2, circulatory disorders. Such as anemia, poor blood supply can show lips black. 3, respiratory dysfunction, such as asthma can show lips black. 4, heart disease, because of myocardial ischemia, insufficient blood supply, can show lips black. In addition, vitamin deficiency (such as lack of vitamin C), hepatitis, long-term fatigue, these conditions will also show. Therefore, lips black, to go to the hospital, according to the history and related tests to determine the cause, correct treatment.