Why Are My Fingernails Blue?

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If you’ve ever noticed that your fingernails have turned a blueish color, it may that you have a condition known as cyanosis. Cyanosis is caused by the lack of oxygen in the blood. It can affect people of all ages, even newborns, and can cause a blue discoloration in other parts of the body including the lips, ears, and fingertips.

Thie article looks at the types, symptoms, and causes of cyanosis and provides an overview of the tools doctors use to diagnose cyanosis and the underlying cause.

Potential Causes of Blue Fingernails

Verywell / Theresa Chiechi

Types of Cyanosis

Cyanosis is a symptom of hypoxemia, which occurs when you haven’t received enough needed oxygen in your blood. This is often in people with advanced chronic obstructive pulmonary disease (COPD), but can also be due to conditions like pneumonia or asthma, among others.

Hypoxia is diagnosed by measuring blood oxygen levels through an arterial blood gas test (ABG) or pulse oximetry, using a sensor that measures the oxygen in your blood.

Cyanosis and its related purple and blue skin discolorations develop when arterial blood oxygen levels drop.

Cyanosis in Newborns

Cyanosis can be found in infants and young children. Peripheral cyanosis can be a benign discoloration of the baby’s feet and hands. Transient central cyanosis is common and can often clear away within five to 10 minutes of birth. Central cyanosis that lingers on however can be serious. Discoloration of the lips and tongue and could indicate the baby has not received sufficient pulmonary blood flow or oxygen intake, among other serious concerns.


Separate from these other types of cyanosis is pseudocyanosis. This is when blue discoloration results from outside causes that can mimic that of a lack of oxygen to the body’s blood. For instance, there have been examples of the ingesting of metals like iron causing this.

Additionally, consuming certain drugs and toxins can cause the body to mimic the peripheral and central cyanosis from lack of oxygenation in the bloodstream.

Cyanosis Symptoms

Just to be clear, cyanosis is not a disease, but a symptom of other conditions. Your blood transitions from a healthy bright red to a darker red color when it is deprived of needed oxygen. When this happens, your skin will have that blue tinge.

While your fingernails are one of the most common areas of the body where the effects of cyanosis will be most clear, other parts of the body can be impacted. This includes your tongue, lips, skin, ears and gums.

If the blue and purplish discoloration is accompanied by other symptoms like finger clubbing, chest pain, or breathing difficulties, it can help pinpoint what underlying cyanosis you have.

When to Call a Healthcare Provider

You should call 911 or seek emergency medical care if your cyanosis symptoms are accompanied by:

  • Chest pain
  • Profuse sweating
  • Clammy skin
  • Shortness of breath
  • Difficulty breathing
  • Dizziness or fainting

These could all be signs of a medical emergency like a heart attack or pulmonary embolus. 


If you have cyanosis and notice your fingertips or other areas of your body are showing signs of a blue or purple discoloration, it could be a sign of a more serious underlying condition or it might mean nothing at all.

Cyanosis is highly variable. Your fingernails might turn blue just temporarily once exposed to a quick shift to colder temperatures that cause your blood vessels to constrict.

More serious underlying conditions can show themselves in the form of persistent cyanosis as a result of either a lack of oxygen sent to the blood, a restriction of blood flow in your blood vessels, or a reduction in cardiac output. These would signify more serious health problems that would need the attention of your healthcare provider and medical team. 

Here are some of the key causes of cyanosis, broken down by organ system in the body:

Organ System Condition
Lungs Asthma, bronchiolitis, COPD, croup, high altitude, extensive pneumoniainterstitial lung disease (ILD), pulmonary edema, pulmonary embolism
Heart Congenital heart disease, congestive heart failure, shock
Blood vessels Cold exposure, peripheral artery disease, pulmonary arteriovenous malformations, Raynaud's phenomenon
Blood cells Carbon monoxide poisoning, methemoglobinemia, polycythemia vera, sulfhemoglobinemia


When aiming to diagnose cyanosis, your healthcare provider will break the process up in three steps:

Physical Exam

They’ll check for finger clubbing, which could suggest congenital heart disease, bronchiectasis and chronic lung infection. You’ll be assessed for any other cardiac or respiratory symptoms.

Review of Medical History

Your healthcare provider will check your family history. You’ll also be asked about the timing of the onset of your symptoms. This will help a healthcare provider know how and when this might have started and even determine whether this is congenital or an acquired condition. 

Blood Oxygen

They will perform blood oxygen tests in the form of arterial blood gas (ABG) tests, which show the partial pressure of dissolved oxygen in your blood and saturation of hemoglobin levels. They’ll also conduct a pulse oximetry, which will measure the absorption of light at the two wavelengths that correspond to oxyhemoglobin and deoxyhemoglobin.

A pulse oximetry needs to be done with an ABG test since it can have a false-positive reading in people with peripheral cyanosis. This is due to the fact that abnormal hemoglobin levels are not picked up by a pulse oximetry test. Combining the two will give the most accurate assessment possible.

Additional tests and imaging studies might be performed beyond these three assessments. This might be due to your healthcare provider’s initial findings and to confirm suspected causes for your cyanosis. 

A Word From Verywell

As you can tell, that blue tinge on your fingernails or elsewhere on your body could before a variety of causes. Cyanosis is highly varied and treatment for it is based on the underlying cause. Cyanosis is not a disease in and of itself. 

The skin discoloration associated with cyanosis might just be a temporary event brought about by cold weather. That being said, this shouldn’t be brushed aside as an unimportant health concern if. You don’t know the cause.

As with any other strange, unusual symptom you might experience, please consult a healthcare provider. Do this even if your cyanosis resolves on its own. Persistent cyanosis suggests a more serious medical condition and should be investigated through proper medical attention. 

Frequently Asked Questions

  • What is cyanosis?

    Cyanosis is when skin, nailbeds, or lips turn a shade of blue, purple, or grayish. This is due to blood carrying less oxygen, which means bodily structures such as organs might not be receiving enough oxygen. It is rarely considered life threatening, but finding out the underlying cause should still be considered a priority.

  • How does anemia affect fingernails?

    Iron deficiency anemia may cause one or more fingernails to have raised ridges, become thin, and curve inward. On its own, this may not be enough to diagnose anemia, but if you experience other symptoms of anemia alongside changes in nail structure, contact a healthcare provider.

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7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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