Cyanosis: Causes, Symptoms, and When to Seek Emergency Care

Cyanosis is a bluish or purplish discoloration of the skin, lips, nail beds, or mucous membranes resulting from inadequate oxygenation of the blood. It occurs when deoxygenated hemoglobin concentration exceeds approximately 5 g/dL in capillary blood.

Types of Cyanosis

• Central cyanosis: Affects the lips, tongue, and trunk; indicates systemic hypoxemia (low arterial oxygen saturation). Causes include severe lung disease (COPD, pneumonia, pulmonary edema), congenital heart defects (right-to-left shunts), and high-altitude exposure.
• Peripheral cyanosis: Affects the extremities (fingers, toes, nose, ears); caused by reduced peripheral blood flow or increased oxygen extraction. Common in cold exposure, shock, heart failure, or peripheral vascular disease.

When to Seek Emergency Care

Sudden onset of central cyanosis—especially with shortness of breath, chest pain, confusion, or loss of consciousness—is a medical emergency. Call emergency services immediately. Chronic or peripheral cyanosis should be evaluated promptly by a healthcare provider to determine the underlying cause.