are blue lips always a sign of cyanosis
Blue lips occur when the skin on the lips takes on a bluish tint or color. This generally is due to either a lack of oxygen in the blood or to extremely cold temperatures. When the skin becomes a bluish color, the symptom is called cyanosis. Most commonly, blue lips are caused by a lack of oxygen in the blood. This may happen when you are at high altitude or if you are choking, or it may be due to chronic underlying conditions such as lung diseases or chronic heart defects.