Cyanosis Causes and Symptoms- When to Seek Help

Last Updated on April 26, 2025

Cyanosis is a bluish discoloration of the nails, skin, and/or mucosa. The term is derived from the Greek word cyanos which means dark blue.

Cyanosis is a medical term for the bluish discoloration of the skin, lips, or nails. It happens when there isn’t enough oxygen in the blood to properly nourish the body’s tissues. While sometimes mild and temporary, cyanosis can also signal serious underlying conditions that need immediate medical attention.

It manifests due to the increased amount of reduced hemoglobin. Hemoglobin is involved in the transportation of oxygen from the lungs to the tissues.Thus high levels of deoxygenated hemoglobin within the superficial vessels [dermal capillaries and subpapillary venous plexus] cause this bluish appearance.

It must be noted that cyanosis is a manifestation of some underlying condition and not a disease itself. Though the bluishness warrants immediate correction for it can be dangerous if unchecked, the underlying conditions should be looked for and managed as well, wherever feasible.

The bluishness is best seen where the overlying epidermis is thin and the area has a rich network of blood vessels. These are

• Lips
• Tip of the nose
• Cheeks
• Ears
• Oral mucous membranes

The bluishness is more likely to be seen in lighter skin.

Recognizing cyanosis causes and symptoms early can help prevent dangerous complications.

What Is Cyanosis?

Normally, oxygen-rich blood gives our skin a healthy pinkish color.

When blood is low in oxygen, it becomes darker and gives the skin a bluish hue, especially noticeable in areas with thinner skin like lips, fingertips, or toes.

In the lung, oxygen attaches to it and it becomes oxygenated hemoglobin or oxyhemoglobin. This oxygenated blood gives a red appearance. In the tissues, oxygen is given out and hemoglobin is now without oxygen, called unoxygenated hemoglobin deoxyhemoglobin, or reduced hemoglobin (RHb).

An amount of reduced hemoglobin of more than 5 g/dL in capillary blood would show symptoms of cyanosis.

In  in patients with moderate to severe anemia, cyanosis occurs late and may not occur until the oxygen saturation levels have dropped to critical levels as lesser hemoglobin is reduced.

Other manifestations of hypoxemia like respiratory symptoms and mental status changes, may appear earlier than cyanosis in patients with anemia. In severe anemia, even the patient may die of hypoxemia without manifestation of bluishness.

Types of Cyanosis

• Peripheral
  • Bluish discoloration of the hands and feet
  • Due to decreased peripheral blood flow.
• Central
  • Bluishness all over the body
  • Noticed at lips, tongue, and sublingual region clearly [below tongue]
• Mixed
  • Manifests as both central and peripheral bluishness
• Cyanosis due to abnormal pigments
  • • A type of central cyanosis due to abnormal pigments in the blood

Common Causes of Cyanosis

Understanding why cyanosis occurs can help guide quick action. Common causes include:

• Lung Conditions: Diseases like pneumonia, chronic obstructive pulmonary disease (COPD), or asthma attacks can reduce oxygen intake.
• Heart Problems: Congenital heart defects, heart failure, or severe arrhythmias can prevent proper blood circulation.
• Circulatory Issues: Blood clots, Raynaud’s disease, or deep vein thrombosis can reduce blood flow to the limbs.
• Exposure to Cold: Cold temperatures cause blood vessels to constrict, slowing blood flow to the skin.
• Blood Disorders: Certain conditions, like methemoglobinemia, sulfhemoglobinemia, and carboxyhemoglobinemia, can alter the blood’s ability to carry oxygen [1].
• Anatomical shunts: cause venous blood to mix with arterial blood like Fallot’s tetrad, pulmonary arteriovenous malformations, multiple intrapulmonary shunts
• Drug overdose: Benzodiazepines, cyanide
• High Altitude: Reduced oxygen levels

Peripheral cyanosis is caused by all the conditions that cause central cyanosis. Other causes are exposure to cold [hypothermia], Raynaud’s phenomenon (A disorder that causes your blood vessels to narrow on cold exposure,) and arterial or venous obstruction

Clinical Presentation

Bluish skin is often the first sign, but other symptoms can provide important clues. These symptoms are-

• Shortness of breath
• Chest pain
• Rapid heartbeat
• Confusion or dizziness
• Fatigue
• Numbness or tingling in hands and feet

If cyanosis develops suddenly or is accompanied by breathing difficulty or chest pain, it could be a medical emergency [2].

When to Seek Immediate Medical Attention

Call for urgent help if you notice:

• Bluish discoloration spreading across the body
• Difficulty breathing
• Chest pain
• Rapid worsening of symptoms
• In infants, pay close attention to bluish lips, tongue, or a floppy body — these require immediate evaluation [3].

Evaluation of Patient and Diagnostic Workup

Cyanosis is  the manifestation of some underlying disorder or condition. The evaluation begins with clinical history and examination.

Presentation of the condition may indicate the probable causes.

Best places to look for cyanosis are cheeks, nose, ears, oral mucosa and nails of hand and feet

A thorough evaluation of the heart and lungs should be done.

A patient with cyanosis should be thoroughly investigated.

• Arterial Blood Gases: It measures oxygen and carbon dioxide levels in blood, besides other parameters. It will reveal the presence of hypoxemia
• Pulse oximetry: Non-invasive way to know and monitor oxygen levels, but gives false readings in methemoglobinemia. Pulse co-oximetry is a better tool when abnormal hemoglobin is suspected
• Complete Blood Count – Hemoglobin level is increased with chronic cyanosis.  White cell count is increased in pneumonia and pulmonary embolism.
• ECG: To rule out cardiac abnormalities.
• Chest X-ray: It can rule out lung diseases like pneumonia, pulmonary infarction, and cardiac failure.
• Ventilation-perfusion scan or pulmonary angiography to rule out  pulmonary causes like infarction
• Echocardiography for cardiac defects.
• Hemoglobin spectroscopy to look for methemoglobinemia and sulfhemoglobinemia.
• Digital subtraction angiography to rule out acute arterial occlusion.
• Duplex Doppler or venography to find acute venous occlusion.

Management

Early recognition of cyanosis causes and symptoms makes a big difference. Cyanosis indicates abnormally low oxygen in the blood. Therefore, this requires immediate attention. Oxygen can be given by the regular nasal cannula or high-flow nasal cannula.

In severe cases, assisted ventilation may be required.

Along with this, electrolytes and metabolites should be corrected as well.  For generalized cyanosis, the patient should be put on supplemental oxygen. If cyanosis involves only a single limb or hand/foot, this is often due to occlusion of the vessels, and accordingly, appropriate measures should be taken.

Definitive treatment focuses on correcting the underlying problem:

• Medications for heart or lung conditions
• Sometimes, simple warming and restoring normal circulation is enough if cold exposure is the only cause.
• For congenital heart disease – surgical intervention is often needed.
• For methemoglobinemia, the standard treatment is methylene blue. This is converted in the body to leucomethylene blue which reduces methemoglobin to normal hemoglobin.
• Exposure to toxic metals or drugs should be stopped.

Can Cyanosis Be Prevented?

In many cases, prevention is about controlling underlying diseases. For example-

• Managing asthma, heart conditions, and chronic lung diseases effectively
• Avoiding extreme cold without proper protection
• Staying physically active to keep circulation healthy
• Quitting smoking to improve lung and blood vessel health [4]

Special SituationsInvolving Cyanosis

Differential Cyanosis

It is the term used for conditions where cyanosis is present in certain parts and absent in others. it is seen in patent ductus arteriosus and its different presentation in conjuction with other conditions. Depending on that, cyanosis can occur in

• Lower limbs only
• Upper limbs only
• Cyanosis of left upper and both lower limbs

Pseudocyanosis

Pseudocyanosis is the term used when there is a bluish tinge to the skin and/or mucous membranes but there is no hypoxemia or peripheral vasoconstriction.

It should be considered when there is no heart or lung disease and the skin does not blanch under pressure.

It can be caused by

• Metals ingestion
  • Silver
  • Lead
• Drugs
  • Phenothiazines
  • Amiodarone
  • Chloroquine hydrochloride

When Cyanosis Does not Occur despite Decreased Oxygen Levels

• Severe anemia
  • The critical amount of hemoglobin is not reduced in spite of saturation
  • Other life-threatening symptoms may develop before it occurs
  • In carbon monoxide poisoning, carboxyhemoglobin prevents the reduction of oxyhemoglobin, and the former has a cherry red color. Hence, there is no cyanosis.

References

1. Mayo Clinic. Cyanosis: Symptoms, Causes, and Diagnosis. [Link]
2. World Health Organization (WHO). Hypoxia and its clinical signs.
3. MedlinePlus. Cyanosis in infants and adults. U.S. National Library of Medicine. [Link]
4. Smith B, Carter D. Recognition and Management of Central Cyanosis in Adults. American Journal of Medicine. 2023.