There are several reasons for the black and purple lips of boys: first, darker skin tone: the color of the lips will also be black and purple. Second, smoking: If boys often smoke, it will also lead to black lips. Third, heart disease: heart disease, poor heart blood supply, low oxygen content in the blood, will also appear black and purple lips. Fourth, poor lung function: such as slow obstructive pulmonary, ventilation dysfunction, etc. will also cause lack of oxygen, resulting in black and purple lips. For the sake of health, if you find black purple lips, you must exclude the causes of heart and lung, do electrocardiogram, lung function test, and do a full range of physical examination every 0.5-1 years, so that certain diseases of the body can also be detected and treated early.