If the patient’s lips are the color of pig liver, it usually belongs to the condition of blue lips. There are usually several reasons for cyanotic lips: firstly, the element of food poisoning should be considered, for example, there will be cyanotic lips when nitrite poisoning occurs. Secondly, some factors of cardiogenic diseases, such as unstable angina pectoris, myocarditis, pericarditis, heart valve disease, congenital heart disease, hypertrophic obstructive cardiomyopathy, will have coronary artery ischemia, stenosis, insufficient blood supply, and lead to blue lips. In addition, for respiratory system diseases, such as chronic bronchiectasis, chronic obstructive pulmonary emphysema, chronic pulmonary heart disease, and pulmonary hypertension, the condition of pig liver colored lips may also occur due to a decrease in the patient’s arterial blood oxygen saturation. Patients who have significant anemia will also have the above symptoms.