Blue lips are typically due to low blood oxygen levels that can be caused by blood clots, high altitude levels, cold exposure and lung conditions, according to MedlinePlus. Blue lips can also occur in individuals who have drowned or experience near-drowning.
Additional medical conditions that may contribute to blue lips include carbon monoxide poisoning and pneumonia, according to Healthline. Testing procedures that measure oxygenation levels of the blood can help to determine the specific underlying causes of the condition. It is important for individuals with blue lips to seek immediate medical attention if symptoms are accompanied by excessive sweating, breathing disturbances, numbness of the hands or fingers, vertigo, or chest pain.
Blue lips can also indicate Raynaud's disease, a condition that causes blood vessel spasms and color changes in the skin, the Mayo Clinic suggests. In addition to the lips, the condition can also affect the hands and feet. During a blood vessel spasm, the affected skin typically turns white, followed by a bluish tint. When circulation is restored, the affected areas may tingle and turn red. However, the condition does not always cause three separate color changes of the skin. Raynaud's disease attacks are commonly triggered by cold exposure, but can also be triggered by stress. Individuals with carpal tunnel syndrome may also experience symptoms of Raynaud's disease.