Vitamin K for Newborns: A Safe Shot That Saves Lives
Infants are at risk of spontaneous bleeding during the first six months of life, including brain bleeds that result in brain injury and death. This used to be called hemorrhagic disease of the newborn. Today we know this as vitamin K deficiency bleeding.
Since 1961, most infants born in the United States have received a single vitamin K injection shortly after birth. This continues to be recommended by the American Academy of Pediatrics, as the vitamin K shot is both safe and highly effective. Yet over the past decade, increasing numbers of parents have declined this standard newborn treatment. As a result, physicians have seen cases of vitamin K deficiency bleeding again, including devastating brain hemorrhages that caused permanent neurologic injury or the death of these infants.
As a pediatrician, I have heard many arguments against vitamin K administration, so I would like to clarify what vitamin K does and discuss concerns about it.
Why Newborns Need Vitamin K
Vitamin K is a fat-soluble vitamin that is essential for the activation of multiple proteins involved in blood clotting. Without adequate vitamin K, the body's clotting system cannot function properly, increasing the risk of bleeding without injury.
Newborn infants are born with very low vitamin K stores. They receive limited vitamin K from the placenta during pregnancy, and breast milk contains relatively small amounts.
The root cause of vitamin K deficiency bleeding in infants is exactly what the name implies: vitamin K deficiency.
Without vitamin K prophylaxis, per the CDC, early and classical vitamin K deficiency bleeding occurs in 1 in 60 to 1 in 250 newborns. Late vitamin K deficiency bleeding is less common. Without the shot, roughly 1 in 15,000–25,000 infants develop late vitamin K deficiency bleeding; with it, there is a 98% risk reduction. Rare cases of it have occurred in infants with liver disease or malabsorptive disease.
The Three Forms of Vitamin K Deficiency Bleeding
Early vitamin K deficiency bleeding
Early vitamin K deficiency bleeding occurs within the first 24 hours after birth. It can range from mild to severe and is most often associated with maternal medications that interfere with vitamin K metabolism, including warfarin (Coumadin), certain anticonvulsants, and some antibiotics.
Classic vitamin K deficiency bleeding
Classic vitamin K deficiency bleeding occurs between the second day of life and the end of the first week. Bleeding may be mild, such as bruising or oozing from the umbilical cord, or severe enough to involve internal organs and the abdomen.
Late vitamin K deficiency bleeding
Late-onset vitamin K deficiency bleeding occurs from one week to six months of age, most commonly between two to eight weeks of age, and is the most feared form of the disease.
Approximately 30% to 60% of these cases involve spontaneous bleeding into the brain. These hemorrhages can result in seizures, permanent neurologic disability, developmental delays, and death. Approximately 20% of affected infants die from their bleeding complications.
The tragedy is that these events are largely preventable with a simple injection given shortly after birth.
Common Concerns about Vitamin K
Concern OneVitamin K thickens the blood and prevents stem cells from the umbilical cord from reaching areas that need repair after birth. What the evidence shows:Vitamin K does not "thicken" the blood. Blood viscosity remains unchanged after vitamin K administration. Vitamin K simply allows clotting proteins that are already present in the body to function normally. This misconception may stem from the fact that vitamin K is used to reverse the effects of warfarin (Coumadin), a medication often called a "blood thinner." This is a misnomer. Warfarin does not make the blood thinner; it prevents clotting by blocking vitamin K activity. Restoring vitamin K simply restores normal clotting function. |
Concern TwoBreast milk contains vitamin K, so supplementation is unnecessary. What the evidence shows:Although breast milk does contain vitamin K, the amount is relatively low. Exclusively breastfed infants are at higher risk of late vitamin K deficiency bleeding because they continue to have limited vitamin K intake during early infancy. |
Concern ThreeOral vitamin K works just as well as the injection. What the evidence shows:To approach the effectiveness of the injection, oral regimens require multiple doses over weeks to months. Missed doses or absorption problems can leave an infant unprotected. Studies in Europe show the occurrence of late-onset vitamin K deficient bleeding is around 3 per 100,000, depending on the oral regimen used. This rate is still higher than with the shot, and several countries, including Sweden, switched from oral regimens to the injection as standard because of this. |
Concern FourVitamin K has a boxed warning, so it must be dangerous.
What the evidence shows:The boxed warning applies to rare hypersensitivity reactions (anaphylaxis) associated with intravenous administration, primarily in adults. Anaphylaxis in newborns from vitamin K shots is extremely rare. There is one non-fatal case report of anaphylaxis after a baby in Turkey got a vitamin K shot in 2014. There are 3.6 million births in the US each year and almost all of these newborns receive a vitamin K injection soon after they are born. There are no reports of anaphylaxis in the US in these infants. |
Concern FiveVitamin K causes leukemia.
What the evidence shows:This concern originated from a study published in 1990 that suggested a possible association between vitamin K administration and childhood leukemia. Multiple subsequent studies failed to demonstrate a causal relationship. Professional medical organizations worldwide continue to recommend newborn vitamin K prophylaxis because the evidence does not support a link between vitamin K injections and childhood cancer. Additionally, the injection contains vitamin K1 (phylloquinone), a naturally occurring form of vitamin K. This differs from vitamin K3 (menadione), a synthetic compound that is not used for routine newborn prophylaxis. |
Concern SixThe dose of vitamin K given to newborns is excessive. What the evidence shows:The standard newborn dose for full term infants is 1 mg for term infants, and 0.5 mg for many premature infants. These doses reliably raise levels and prevent bleeding. Higher-than-physiologic levels are cleared without known harm, including to the liver, kidneys, or brain. |
Concern SevenThe ingredients in the injection are harmful. What the evidence shows:Multidose formulations contain small amounts of benzyl alcohol as a preservative, along with dextrose, water, oils, and acetic acid. Preservative-free formulations are available and are recommended for newborns when available. The vitamin K shot does not contain aluminum or thimerosal. |
Concern EightThe shot causes pain and distress in newborns.
What the evidence shows:We can mitigate the pain and distress from the shot by having parents hold the infant, especially skin to skin, and breastfeed during or immediately after shot administration. |
Bottom Line
Vitamin K deficiency bleeding is uncommon, but when it occurs, the consequences can be life changing. A healthy infant can appear perfectly normal one day and suffer a spontaneous, devastating brain hemorrhage the next day.
A single vitamin K injection at birth can prevent an otherwise healthy baby from suffering a devastating and potentially fatal hemorrhage. If you are expecting a baby and have questions about vitamin K prophylaxis for your newborn, please talk to your pediatrician and healthcare team. I assure you they want your baby to be safe and healthy and would love to have a conversation about this with you.
Sources
Ardell S, Offringa M, Ovelman C, Soll R. Prophylactic Vitamin K for the Prevention of Vitamin K Deficiency Bleeding in Preterm Neonates. Cochrane Database of Systematic Reviews. 2018.
FDA. Phytonadione Drug Label Update. 2026.
Hand I, Noble L, Abrams SA. Vitamin K and the Newborn Infant. Pediatrics. 2022.
Jullien S. Vitamin K prophylaxis in newborns. BMC Pediatrics. 2021.
Lakhotia R, Raghuveer TS. The Need for Vitamin K Among US Newborns. JAMA Pediatrics. 2026.
Rogers TP, Fathi O, Sánchez PJ. Neonatologists and Vitamin K Hesitancy. Journal of Perinatology. 2023.
Simatou E, Tsamantioti E, Hallström A, et al. Vitamin K Prophylaxis in Newborns and Bleeding in Infancy. JAMA Pediatrics. 2026.
Weddle M, Empey A, Crossen E, et al. Are Pediatricians Complicit in Vitamin K Deficiency Bleeding? Pediatrics. 2015.
Witt M, Kvist N, Jørgensen MH, et al. Prophylactic Dosing of Vitamin K to Prevent Bleeding. Pediatrics. 2016.
This post is for educational purposes only and does not constitute medical advice. Please consult a qualified healthcare provider for personalized guidance.
©2026 Evexeya Health | Madison, WI | evexeyahealth.com
