Why Are My Fingernails Blue?

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If you have blue fingernails, it may be due to an underlying condition known as cyanosis. This condition is caused by a lack of oxygen in the blood. In addition to fingernails, cyanosis commonly impacts the hands, soles of the feet, and mouth. It can affect people of all ages, including newborns.

Potential Causes of Blue Fingernails.

Verywell / Theresa Chiechi

This article looks at the different types of cyanosis. It also explores symptoms, potential causes, as well as how this condition is diagnosed.

What Are the Different Types of Cyanosis?

There are three types of cyanosis:

  • Central: Central cyanosis is blue discoloration that is seen on the tongue, lips, other areas within the mouth, as well as parts of the eye.
  • Peripheral: This type of cyanosis is seen as blue or purple discoloration in the nails, fingers, and toes. Also called acrocyanosis.
  • Differential: This type of cyanosis is seen as blue discoloration in certain areas of the body, such as the upper or lower body, or right or left side of the body.

Cyanosis in Newborns

While cyanosis may be commonly seen in newborns, central cyanosis that lasts longer than 10 minutes may be associated with life-threatening conditions and is considered an emergency.

What Are Symptoms of Cyanosis?

Where on the body cyanosis shows up will vary depending on the specific type. The condition triggering cyanosis may also lead to other symptoms.

Central Cyanosis

Central cyanosis is blue discoloration on the tongue, lips, other areas of the mouth, as well as the eyes. This type of cyanosis is associated with heart and breathing conditions, as well as drug use.

While symptoms will vary due to the underlying condition, some possible associated symptoms include:

Peripheral Cyanosis

Peripheral cyanosis is blue or purple discoloration in the fingers, toes, and nails. It can also impact the nose. This type of cyanosis is associated with the same underlying conditions as central cyanosis. It is also associated with cold exposure and Raynaud phenomenon, a condition that causes decreased blood flow to certain parts of the body.

While symptoms will vary due to the underlying condition, possible associated symptoms may include:

Differential Cyanosis

Differential cyanosis leads to blue discoloration in specific areas of the body. This means that only certain parts of the body, such as the right or left side, or upper or lower body will be impacted. This type of cyanosis is associated with structural heart issues that are present at birth.

Associated symptoms may include:

Infants may also have difficulty gaining weight, have feeding problems, and have a decreased appetite.

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, or one or more blood clots in the lungs.

What Causes Blue or Purple Nails? 

If you notice areas of your body showing signs of blue or purple discoloration, it could be associated with a more serious underlying condition.

Causes of Central Cyanosis

Central cyanosis is caused by a lower than typical level of oxygen in your blood. This is also known as hypoxemia. This can occur due to:

Causes of Peripheral Cyanosis

Peripheral cyanosis may be caused by slow or blocked blood flow in areas other than the brain and heart. This impacts oxygen delivery. This can be due to the same causes as central cyanosis, as well as:

  • Congestive heart failure, or when the heart doesn’t pump enough blood for your body’s needs
  • Cold exposure
  • Blockage in a vein or artery

Causes of Differential Cyanosis

Differential cyanosis is associated with heart structure issues that are present from birth. Some may include:

  • Coarctation of the aorta, or a narrowing in a part of the heart’s main artery
  • Interrupted aortic arch, a rare condition where the aorta doesn’t fully form
  • Patent ductus arteriosus, or an abnormal hole in the heart that impacts how blood flows to the lungs

Diagnosing Cyanosis

When diagnosing cyanosis, your healthcare provider will do a physical exam, review your medical history, and run certain tests.

Your healthcare provider will do a physical exam to determine which type of cyanosis you may have, as well as what the potential underlying condition may be. They will take into consideration the exam room’s temperature, as well as the lighting while conducting this exam.

Your healthcare provider will go over your medical history. Along with other questions, you’ll be asked about when your symptoms began. This will help them determine whether or not this is due to a condition that you’ve had since birth.

Diagnostic Tests

Tests that may be used to diagnose this condition:

  • Pulse oximetry: This noninvasive test uses a probe or sensor to estimate the amount of oxygen available in the blood. It may be used to check for central and peripheral cyanosis, as well as for heart structure issues that may indicate differential cyanosis.
  • Arterial blood gas analysis (ABG): This blood test shows oxygen and carbon dioxide levels in the blood, as well as the blood’s acidity level. This test also looks at hemoglobin. This may be used to check for central and peripheral cyanosis.
  • Computed tomography scan and X-rays: These imaging tests may check for peripheral cyanosis, as well as lung, and heart conditions.
  • Echocardiogram: This test uses sound waves to take pictures of your heart. This checks for structural issues and heart functioning.

Other tests may be performed based on your results.

A pulse oximetry needs to be done with an ABG test since it can have a false-positive reading in people with peripheral cyanosis.

Differential Diagnosis

During the diagnostic process, your healthcare provider will rule out a condition called pseudocyanosis. This is not true cyanosis, even though it presents in a similar way. Ingesting metals like iron, as well as some medications may cause this.


If you have blue discoloration on your nails, or other areas of your body, you may have cyanosis. This is caused by a lack of oxygen in the blood.

There are three different types of cyanosis and each leads to blue discoloration in different areas of the body. The underlying condition causing cyanosis may also lead to symptoms.

To diagnose cyanosis, your healthcare provider will review your medical history, do a physical exam, and run specific tests.

A Word From Verywell

A blue tinge on your fingernails or elsewhere on your body could be due to a variety of causes. Cyanosis is highly varied and treatment for it is based on the underlying cause.

The skin discoloration associated with cyanosis might just be a temporary event brought about by cold weather. However, this shouldn’t be brushed aside as an unimportant health concern. Be sure to check in with your healthcare provider even if your symptoms go away quickly.

Frequently Asked Questions

  • What does it mean when your fingernails turn blue?

    Cyanosis is when parts of the body turn a shade of blue or purple. This is due to blood carrying less oxygen. This means bodily structures such as organs might not be receiving enough oxygen.

  • How does anemia affect fingernails?

    Iron deficiency anemia may cause one or more fingernails to have raised ridges, become thin, and curve inward.

  • Should I be worried if my nails become purpler or blue?

    If it is temporary and due to the cold, it may not be something to worry about. However, it’s always best to check in with your healthcare provider to make sure there isn’t an underlying condition causing this symptom.

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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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By Brian Mastroianni
Brian Mastroianni is a health and science journalist based in New York. His work has been published by The Atlantic, The Paris Review, CBS News, The TODAY Show, Barron's PENTA, Engadget and Healthline, among others.