Cyanosis is a bluish color to the skin or mucus membranes due to a lack of oxygen in the blood.

Lips - bluish; Fingernails - bluish; Cyanosis; Bluish lips and fingernails; Bluish skin

The coloration of the skin is caused by the amount of pigment in the skin and the blood flowing through it. Blood that is saturated with oxygen is bright red. Blood that has lost its oxygen is dark bluish-red. People whose blood is low in oxygen tend to have a bluish color to their skin, called cyanosis.

Cyanosis can be caused by:

• Lack of oxygen (such as in suffocation or cyanotic heart disease)
• Abnormal hemoglobin (such as methemoglobinemia)
• Toxins (such as cyanide)

Most cyanosis occurs as a result of:

• Heart disease (such as congestive heart failure)
• Lung disease
• A potentially fatal event, such as the stopping of heart and lung function (cardiopulmonary arrest)

Mild cyanosis may be hard to detect. Usually the oxygen saturation of the blood has to drop from the normal level of nearly 100% to below 90% before cyanosis occurs.

In dark-skinned people, cyanosis may be easier to see in the mucus membranes (lips, gums, around the eyes) and nail beds, rather than in the skin. It may also appear on the feet, nose, and ears.

People with a problem called Raynaud's phenomenon may develop a blue color in their fingers or hands when they are exposed to cold.

A blood clot that blocks the blood supply to a leg, foot, hand, or arm will cause bluish skin.

Other causes of bluish skin (cyanosis) include:

Problems with the lungs

• Pneumonia (severe)
• Bronchiolitis
• Chronic obstructive pulmonary disease (COPD), asthma, and other chronic lung problems
• Blood clot in the arteries of the lungs (pulmonary embolism)
• Hyaline membrane disease due to prematurity
• Pulmonary hypertension

Problems with the airways leading to the lungs

• Choking on something stuck in the airways
• Croup
• Epiglottitis

Problems with the heart

• The heart stops working (cardiac arrest)
• Heart failure
• Heart defects that are present at birth (congenital)

Other problems

• Exposure to cold air or water
• High altitudes
• Breath-holding
• Seizures that last a long time
• Drug overdoses (narcotics, benzodiazepines, sedatives)
• Toxins such as cyanide
• Drowning or near-drowning

For cyanosis caused by exposure to cold, dress warmly when going outside or stay in a well-heated room.

Bluish skin (cyanosis) can be a sign of many serious medical problems and should be taken seriously.

For adults, call your doctor or 911 if you have bluish skin and:

• Your breathing is getting harder, faster, or you cannot get a deep breath.
• You need to lean forward when sitting.
• You are using muscles around the ribs more.
• You have chest pain.
• You are having headaches more often than usual.
• You feel sleepy or confused.
• You have a fever.
• You are coughing up dark mucus.

For children, call the doctor or 911 if your child has bluish skin and:

• Is having a hard time breathing
• The child's chest muscles are pulling in with each breath
• Is breathing faster than 50 to 60 breaths per minute (when not crying)
• Is making a grunting noise
• Is sitting with shoulders hunched over
• Is very tired
• Is not moving around very much
• Has a limp or floppy body
• The nostrils are flaring out when the child breathes
• Loses his or her appetite
• Is irritable
• Has trouble sleeping

Call or visit your health care provider if you have any unexplained changes in the color of your skin or mucus membranes.

Your health care provider will perform a physical examination, which includes listening to your breathing and heart sounds. In emergency situations (such as shock), the patient will be stabilized first.

Medical history questions may include:

• When did it develop?
• Did it develop suddenly?
• Has it been developing slowly?
• Are your lips blue?
• Are your nailbeds blue?
• Is your body blue all over?
• Have you been exposed to cold?
• Have you suddenly gone to a high altitude?
• Have you breathed in anything?
• What other symptoms do you have?
• Do you have difficulty breathing?
• Do you have ankle, feet, or leg swelling?
• Do you have a cough?
• Do you have chest pain?

Tests that may be performed include:

• Arterial blood gas analysis
• Complete blood count (CBC)
• Chest x-ray
• ECG
• Measurement of blood oxygen saturation by pulse oximetry

For shortness of breath and cyanosis, you may receive oxygen.

Bocock J, Kolodzik J. Cyanosis. In: Marx JA, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 6th ed. Philadelphia, Pa: Mosby Elsevier;2006:chap 30.

Kraft M. Approach to the patient with respiratory disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 83.