Blue baby syndrome, also called cyanosis, is a condition in babies in which their skin appears blue or purple tinged. It may be caused by many things like birth defects, heart ailments, or lung diseases.

Blue baby syndrome is a condition some babies are born with or develop early in life. It’s characterized by an overall skin color with a blue or purple tinge, called cyanosis.

This bluish appearance is most noticeable where the skin is thin, such as the lips, earlobes, and nail beds. Blue baby syndrome, while not common, can occur due to several congenital (meaning present at birth) heart defects or environmental or genetic factors.

What causes blue baby syndrome?

The baby takes on a bluish hue because of poorly oxygenated blood. Normally, blood is pumped from the heart to the lungs, where it receives oxygen. The blood is circulated back through the heart and then throughout the body.

When there’s a problem with the heart, lungs, or blood, blood may not be oxygenated properly. This causes the skin to take on a blue color. The lack of oxygenation can occur for several reasons.

Tetralogy of Fallot (TOF)

While a rare congenital heart defect, TOF is a primary cause of blue baby syndrome. It’s actually a combination of four heart defects that can reduce blood flow to the lungs and allow oxygen-poor blood to flow out into the body.

TOF includes conditions like having a hole in the wall that separates the left and right ventricles of the heart and a muscle obstructing the flow of blood from the right ventricle into the pulmonary, or lung, artery.


This condition stems from nitrate poisoning. It is can happen in babies who are fed infant formula mixed with well water or homemade baby food made with nitrate-rich foods, like spinach or beets.

The condition occurs most often in babies under 6 months of age. When this young, babies have more sensitive and underdeveloped gastrointestinal tracts, which are more likely to convert nitrate into nitrite. As nitrite circulates in the body, it produces methemoglobin. While methemoglobin is oxygen-rich, it doesn’t release that oxygen into the bloodstream. This gives babies with the condition their bluish hue.

Methemoglobinemia can also rarely be congenital.

Other congenital heart defects

Genetics cause most congenital heart defects. For example, babies born with Down syndrome often have heart problems.

Issues with maternal health, such as underlying and poorly controlled type 2 diabetes, can also result in a baby developing heart defects.

Some heart defects are also caused for no apparent reason at all. Only a few congenital heart defects cause cyanosis.

What are the symptoms?

In addition to the bluish color of the skin, other symptoms of blue baby syndrome include:

  • irritability
  • lethargy
  • feeding issues
  • inability to gain weight
  • developmental issues
  • rapid heartbeat or breathing
  • clubbed (or rounded) fingers and toes

How is it diagnosed?

Besides taking a thorough medical history and performing a physical exam, your baby’s pediatrician will probably perform a number of tests. These tests will help determine the cause of blue baby syndrome. Tests can include:

  • blood tests
  • chest X-ray to examine the lungs and the size of the heart
  • electrocardiogram (EKG) to look at the electrical activity of the heart
  • echocardiogram to see the anatomy of the heart
  • cardiac catheterization to visualize the arteries of the heart
  • oxygen saturation test to determine how much oxygen is in the blood

How is it treated?

Treatment depends on the cause of the blue baby syndrome. If the condition is produced by a congenital heart defect, your baby will most likely need surgery at some point.

Medication may be recommended as well. These recommendations are based on the severity of the defect. Babies with methemoglobinemia can reverse the condition by taking a drug called methylene blue, which can provide oxygen to the blood. This drug needs a prescription and is usually delivered via a needle inserted into a vein.

How can I prevent blue baby syndrome?

Some cases of blue baby syndrome are a fluke of nature and can’t be prevented. Others, though, can be avoided. Steps to take include:

  • Don’t use well water. Don’t prepare baby formula with well water or give babies well water to drink until they’re over 12 months old. Boiling water won’t remove nitrates. Nitrate levels in water shouldn’t exceed 10 mg/L. Your local health department can give you more information on where to get well water tested.
  • Limit nitrate-rich foods. Foods rich in nitrates include broccoli, spinach, beets, and carrots. Limit the amount you feed your baby before they’re 7 months old. If you make your own baby food and must use these vegetables, use frozen rather than fresh.
  • Avoid illegal drugs, smoking, alcohol, and some medications during pregnancy. Avoiding these will help prevent congenital heart defects. If you have diabetes, make sure that it’s well-controlled and that you’re under a doctor’s care.

What’s the outlook for babies with this condition?

Blue baby syndrome is a rare disorder with a variety of causes. Your doctor may advise anything from no immediate treatment to surgery. Surgery can be very risky when performed on a newborn.

Once the cause is identified and successfully treated, most children with blue baby syndrome can live normal lives with few health consequences.