The reasons for men’s lips black have low environmental temperature, serious lung disease, severe heart failure, Cushing’s syndrome, etc., as follows: 1, low environmental temperature: because the environmental temperature is too low, resulting in the contraction of the skin mucous membranes, such as suddenly entering the cold environment, due to the contraction of the capillaries, it is possible to cause the lips to be black; 2, serious lung disease: such as respiratory failure, pulmonary hypertension, severe Emphysema or chronic obstructive pulmonary disease, due to the decline in lung function, the body’s oxygen content is reduced, can cause purple lips, serious also cause purple earlobes; 3, serious heart failure: can also be manifested as black lips, at this time in addition to black lips, there may also be manifested as swelling of the legs, digestive function decline; 4, Cushing’s syndrome: if the condition is more serious, can also be manifested as black lips as well as skin and mucous membranes. Cushing’s syndrome: if the condition is more serious, it can also show black lips and skin.