Blue fingernails may be due to a low level or lack of oxygen circulating in your red blood cells. Other causes include chronic conditions and cold temperatures.
Having a blue tint to your fingernails is a condition known as cyanosis. It occurs when there isn’t enough oxygen in your blood, making the skin or membrane below the skin turn a purplish-blue color.
Peripheral cyanosis refers to cyanosis of the extremities, like the fingernails and hands, while central cyanosis is a generalized cyanosis that occurs on the body.
When it’s an emergency
Blue fingernails with any of the following symptoms require immediate medical attention:
The skin discoloration could mean that there’s a high level of an atypical form of hemoglobin in your blood. Hemoglobin is the protein responsible for transporting oxygen in your blood.
Cold temperatures can
Blue fingers due to cold temperatures are a typical response to the body’s attempt to keep internal organs at the right temperature.
If your usual nail color returns upon warming up or massaging your hands, the blue color may have been due to that part of your body not getting enough blood supply because of cold temperatures.
However, if fingernails remain blue, an underlying condition or structural difference may interfere with the body’s ability to deliver oxygen-rich blood.
Learn more about causes, treatment, and when to get help.
Health conditions involving the lungs, heart, blood cells, or blood vessels can cause the blue discoloration in your fingernails.
Conditions that can cause cyanosis include the following:
Diseases of the lungs
Lung disease can make breathing difficult and affect the amount of oxygen that reaches your blood. Lung diseases that can cause cyanosis may include:
- chronic obstructive pulmonary disease (COPD), a group of progressive lung diseases that includes emphysema and chronic bronchitis
- asthma, which causes inflammation in the airways
- pneumonia, an infection that leads to inflammation in the air sacs in your lungs
- acute respiratory distress syndrome (ARDS), which occurs when fluid fills the air sacs in your lungs
- pulmonary embolism, a blood clot in the lungs
- genetic diseases, such as cystic fibrosis
Diseases of the heart
Heart disease can affect how much oxygen your blood can carry throughout your body. Possible heart-related causes of cyanosis can include:
- congenital heart disease, a heart abnormality present at birth
- Eisenmenger syndrome, a pulmonary hypertension that results from a congenital heart disease
- congestive heart failure, when the heart can’t pump blood through your body efficiently
Heart disease may also cause symptoms like:
- fatigue
- chest pain
- swelling in your lower extremities from fluid retention (edema)
- increased urination, especially at night (nocturia)
- shortness of breath
- fainting
Atypical blood cells
Conditions that cause atypical blood cells can include:
- methemoglobinemia, a blood disorder that causes your body to produce so much methemoglobin (a type of hemoglobin that can’t bind oxygen) that it begins to replace your normal hemoglobin, and it can be:
- congenital (present at birth)
- acquired, which is a condition that occurs after ingesting certain foods, medications, or chemicals
- polycythemia vera, a type of cancer that causes red blood cells to multiply and increases the risk of blood clots
Atypical blood vessels
Raynaud’s phenomenon is a condition in which blood vessels constrict, restricting blood flow to the extremities. This can cause color changes and make nails appear blue, white, purple, or red.
Many causes of cyanosis require medical intervention, and some can be an emergency.
If you have cyanosis that doesn’t resolve after warming up your body or you have cyanosis that occurs with concerning symptoms, it’s best to get urgent medical attention.
Cyanosis can also be an emergency. Contact 911 or your local emergency services if you have cyanosis in addition to the following symptoms:
- shortness of breath or breathing difficulties
- chest pain
- profuse sweating
- dizziness or fainting
A noninvasive pulse oximeter is the simplest way to measure blood oxygenation. Doctors draw arterial blood gases to measure the amount of oxygen in the blood, which helps determine what factors might contribute to blue fingernails.
Once doctors determine the cause, they can recommend an appropriate treatment.
Treatment involves first identifying the underlying cause so that they can then restore adequate oxygen to the blood.
Blue fingernails, or cyanosis, occur when the blood doesn’t have enough oxygen. They are most often caused by cold temperatures.
Occasionally, it can be caused by medical conditions. These include diseases of the lungs or heart, or atypical blood cells or vessels.
The diagnosis is typically noninvasive, and treatment depends on the underlying cause.