Purple lips in children are commonly associated with congenital heart disease, such as complete transposition of the great vessels, hypoplastic left heart, pulmonary and aortic valve stenosis, and atrial septal defect. Due to malformation of the heart’s vascular pathways, part of the venous blood does not pass through the lungs for oxygenation into the arteries of the body circulation, causing the lips to turn purple.
Secondly, cold weather, poor local blood circulation to the lips, food poisoning, asthma, nitrite poisoning, cardiomyopathy, chronic hyperalgesia, long polyps in the digestive tract, severe anaemia and airway obstruction can all lead to purple lips. If a child has chronic purple lips and has symptoms that continue to worsen, it suggests that a more serious illness may be present and parents should take the child to the hospital promptly.