Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Cyanosis is a medical condition characterized by bluish discoloration of the skin and mucous membranes due to low oxygen levels in the blood. It often indicates underlying respiratory or circulatory issues.
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Cyanosis can be caused by severe allergic reactions leading to anaphylaxis, which impairs breathing.
It is often observed with cardiovascular anomalies that affect oxygen delivery to tissues.
Peripheral cyanosis specifically affects extremities such as fingers and toes and can result from localized problems like Raynaud's phenomenon.
Central cyanosis involves more widespread bluish discoloration, including the lips and tongue, indicating systemic hypoxemia.
Diagnosis of cyanosis may involve pulse oximetry, arterial blood gas analysis, and observation of clinical symptoms.
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Related terms
Hypoxemia: A condition characterized by an abnormally low level of oxygen in the blood.
A severe, potentially life-threatening allergic reaction that can cause respiratory distress.
Raynaud's Phenomenon: A condition causing some areas of the body—such as fingers and toes—to feel numb and cold in response to cold temperatures or stress.