Bilious vomiting means a person’s vomit is yellowish-green, which is the color of bile. Bilious vomiting may mean a person has a blockage somewhere in their gastrointestinal tract.

It can also happen when a person vomits on an empty stomach. Additionally, it often happens in infants who are born with intestinal obstruction.

Parents and caregivers who notice bile-colored vomit in a baby, especially in the first day or two of life, should seek emergency care.

Read more to learn about bilious vomiting, its causes, risk factors, and more.

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Bilious vomiting means that a person’s vomit is the color of bile. This is usually green, yellow, or a mixture of the two. It often has a very bitter taste.

Typically, bilious vomiting is benign, or harmless. It often happens when a person vomits on an empty stomach.

However, in infants, it can be cause for concern. Bilious vomiting in infants may be a sign of a malformation in the gastrointestinal tract.

Bilious vomiting usually happens when something prevents bile from passing normally through the digestive tract. This typically signals some type of obstruction.

One of the most common causes in newborns and young infants is duodenal atresia, a condition where the small bowel does not develop properly. This is a condition infants are born with.

It causes vomiting — often bilious — within the first day or two of life. This typically happens following the first feeding.

Other factors may cause bilious vomiting in both children and adults. They include:

Anyone can vomit bile. Circumstances that increase the risk include:

Vomiting is relatively common, and most people will experience it at some point. Most vomiting is nonbilious, which means vomit is not the color of bile.

Some causes of nonbilious vomiting include:

Nonbilious vomiting is usually not green or yellow. However, it is possible for nonbilious vomiting to still look like bilious vomiting.

A person’s vomit may be many different colors depending on the food they eat, how often they vomit, how much water they have had, and other factors.

In an infant or newborn, doctors usually assume that bilious vomiting is caused by an obstruction somewhere in the intestinal tract. For this reason, they will likely treat bilious vomiting as an emergency.

They will order imaging tests that may include an X-ray, or contrast imaging, which involves injecting dye into the body and then performing a scan.

In adults, doctors will assess the wider context in which bilious vomiting occurs. They may:

  • ask about recent illness or order a pregnancy test
  • ask whether the person vomited on an empty stomach
  • perform an exam to look for other symptoms, such as upper abdominal tenderness
  • order tests to look for gallstones or an obstruction

Treatment depends on the likely cause of a person’s vomiting.

When there is no obvious cause, a doctor may recommend waiting to see if a person improves.

However, in infants, the condition will be treated as an emergency. If doctors determine the cause is a blockage such as duodenal atresia, surgery can treat the condition. Without surgery, a baby may be unable to absorb nutrients, so a doctor may recommend surgery immediately.

Some other potential treatments include:

  • antinausea drugs to stop the vomiting
  • treatment for an underlying infection
  • surgery to remove an obstruction
  • removing the gallbladder if a person has gallstones
  • intravenous (IV) fluids to help a person avoid dehydration

The outlook depends on the cause of the bilious vomiting.

In most cases, the outlook is good with the appropriate treatment. Many people may need no treatment.

For example, a person may vomit bile if they are pregnant and have morning sickness on an empty stomach or vomit on an empty stomach during a stomach virus.

However, there is a risk of dehydration if a person has severe vomiting. A condition called hyperemesis gravidarum, which is a severe type of morning sickness, may cause this. In this case, a person may need antinausea medication or IV fluids.

Bilious vomiting can be concerning, especially if a person does not know the reason for the vomiting. However, it is treatable, and in adults, it may go away on its own.

Parents and caregivers should treat bilious vomiting in newborns and very young babies as a medical emergency requiring immediate care, especially if the vomiting happens after the baby’s first meal. A doctor can determine the cause of the vomiting and treat it accordingly.