What Is Vitamin K Deficiency Bleeding? Causes and Symptoms, Reviewed November 2026

Information verified November 10, 2026, at 5:04 p.m. UTC (UTC+00:00).

Vitamin K deficiency bleeding (VKDB) occurs when a baby has too little vitamin K to make enough proteins needed for normal blood clotting. Bleeding can happen inside or outside the body, including in the brain or intestines, and may begin without an obvious warning.

Current guidance from the Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP) recommends a vitamin K shot shortly after birth to prevent this potentially life-threatening condition. The guidance reviewed for this article describes an established health issue; it does not identify a new outbreak or change in recommendation.

Destaques

• Newborns have low vitamin K stores because little of the vitamin crosses the placenta during pregnancy.
• VKDB can cause bruising or visible bleeding, but serious internal bleeding can occur without earlier signs.
• Late VKDB can occur up to 6 months of age, most often between 2 and 8 weeks.
• A single vitamin K injection after birth is the best way to prevent VKDB.

What happens in vitamin K deficiency bleeding?

Vitamin K helps the liver make several clotting factors, proteins that work together to stop bleeding. When vitamin K levels are too low, the body cannot make enough functional clotting factors. A minor injury, a procedure, or bleeding inside the body may then become difficult to control.

VKDB is the term commonly used for this problem in infants. It was previously called hemorrhagic disease of the newborn. The condition is uncommon in the United States, where most newborns receive vitamin K, but its effects can be severe. According to the CDC’s overview of VKDB, bleeding in the brain can cause permanent injury or death.

What are the symptoms of vitamin K deficiency bleeding?

There may be no warning signs before a serious bleed. When symptoms do appear, they can include:

• Unexplained bruises, especially around the head or face.
• Bleeding from the nose or umbilical cord.
• Skin that looks paler than usual, or pale gums in a baby with darker skin.
• Blood in stool, black and sticky stool, or vomiting blood.
• Irritability, unusual sleepiness, repeated vomiting, or seizures, which can be signs of bleeding in the brain.
• Yellowing of the whites of the eyes after the first three weeks of life.

These signs can have other causes, so they do not establish a diagnosis on their own. A baby with bleeding, seizures, marked sleepiness, or other concerning symptoms needs immediate medical assessment; call 911 for severe symptoms or an emergency. Do not wait for a vitamin supplement to work before seeking care.

When can VKDB occur?

Clinicians describe three forms according to when bleeding begins:

• Early: Within the first 24 hours after birth. It is often associated with certain medicines taken during pregnancy that interfere with vitamin K.
• Classical: From 2 days to 1 week after birth. Bruising and bleeding from the umbilical cord are possible signs.
• Late: From 1 week to 6 months after birth, most commonly at 2 to 8 weeks. It can affect an infant who previously appeared healthy.

Late VKDB is especially concerning because bleeding may occur in the brain. The CDC reports that infants who do not receive the shot at birth are 81 times more likely to develop late VKDB than those who receive it. That comparison describes relative risk; it does not mean that most babies who miss the shot will develop bleeding.

Why are newborns at risk of vitamin K deficiency?

Only a small amount of vitamin K passes through the placenta, so babies start life with limited stores. Their intestinal bacteria are also not yet established. Breast milk contains vitamin K, but the amount alone is not enough to prevent VKDB. This is a reason for vitamin K protection, not a reason to stop breastfeeding.

Risk is greater when a baby does not receive the vitamin K shot, particularly if the baby is exclusively breastfed. Certain medications taken during pregnancy, including some seizure medicines and isoniazid, can interfere with vitamin K. Liver disease or conditions that impair absorption, such as cystic fibrosis, can also increase risk. Having a risk factor does not mean a baby will develop VKDB, and an otherwise healthy-looking baby can still be affected.

Vitamin K deficiency can also occur beyond infancy, although it is rare. Problems absorbing the vitamin and prolonged antibiotic treatment are among possible causes; easy bruising or bleeding can result. The National Library of Medicine’s vitamin K overview provides more information for adults.

How do doctors diagnose and treat VKDB?

A clinician considers the baby’s symptoms, age, feeding, medical history, and whether vitamin K was given at birth. Blood tests can assess clotting. One common test is prothrombin time, reported with or without an INR; a prolonged result can occur with vitamin K deficiency but can also have other causes, including liver disease. Results must be interpreted alongside the rest of the assessment, as explained by MedlinePlus.

Treatment is directed by a medical team and includes vitamin K. Depending on the location and severity of bleeding, a baby may also need blood products, imaging, intensive care, or surgery. Prompt evaluation matters because internal bleeding cannot be reliably ruled out by appearance alone.

How does the vitamin K shot prevent bleeding?

The shot is given into a muscle, usually in the thigh, shortly after birth. The AAP recommends it for all newborns; the CDC says it may be delayed for up to six hours to allow immediate bonding. The injection supplies vitamin K when stores are low and provides protection during early infancy.

The AAP’s parent guidance says oral vitamin K is less reliable because absorption can be inadequate. If a baby did not receive the shot, contact the baby’s clinician promptly to discuss what to do next; do not substitute an over-the-counter product or a breastfeeding parent’s supplements without medical advice.

Frequently asked questions

Can a breastfed baby get enough vitamin K from milk alone?

No. Breast milk contains some vitamin K, but not enough to reliably prevent VKDB. The shot is recommended for breastfed newborns as well as other newborns.

Can VKDB happen after the first week?

Yes. Late VKDB can occur from one week through six months of age, even in a baby who previously seemed well.

Is the newborn vitamin K shot safe?

The CDC and AAP consider it safe. Temporary pain, bruising, or swelling at the injection site can occur; serious allergic reactions are extremely rare. Discuss individual concerns with your baby’s clinician.