Vitamin K and Tongue-tie Division

Vitamin K is routinely offered to newborn babies in the UK to reduce the risk of vitamin K deficiency bleeding (VKDB), a rare but potentially serious bleeding disorder.

For many families, the decision about vitamin K is made shortly before or after birth, at a time when there may already be many new things to consider. Some families accept vitamin K by injection, some choose an oral course, and some decide not to give vitamin K.

Families should be given clear information about what vitamin K does, why newborn babies have relatively low levels, what the different routes of administration involve and what options may remain available if the initial decision changes.

Vitamin K is not a treatment for feeding difficulties or tongue-tie. Its relevance to feeding is therefore limited, although its status can become important when an invasive procedure such as frenulotomy is being considered because bleeding is a recognised potential complication of the procedure.

What is vitamin K?

Vitamin K is a fat-soluble vitamin with several functions within the body. One of its most important roles is in normal blood clotting. Vitamin K is required by the liver to produce several vitamin-K-dependent clotting factors, including factors II, VII, IX and X, which are necessary for the blood to form an effective clot.

Newborn babies begin life with relatively low vitamin K stores. Only a small amount of vitamin K crosses the placenta, and human milk naturally contains relatively little vitamin K. This means that a newborn has limited reserves during a period when the systems involved in maintaining adequate vitamin K levels are still developing.

As infancy progresses, the baby's sources and stores of vitamin K increase. This is a gradual process rather than a particular point at which the risk suddenly disappears, which is one reason why vitamin K deficiency can remain relevant beyond the first few days of life (NICE, 2026a).

Vitamin K deficiency matters because insufficient vitamin K can reduce the liver's ability to produce adequate amounts of the clotting factors needed for normal haemostasis. In a baby with significant deficiency, bleeding can therefore occur without an obvious injury to explain it.

Why are newborn babies offered vitamin K?

Vitamin K deficiency bleeding, or VKDB, is uncommon, but it can be serious and, in some cases, life-threatening. It can occur during the first hours and days after birth or later during infancy.

VKDB is generally described according to when it occurs. Early VKDB occurs within the first 24 hours of life, classical VKDB generally occurs during the first week, and late VKDB occurs from around one week until several months of age. Late VKDB is particularly concerning because bleeding can occur internally, including within the brain, and there may not always be an obvious warning before significant illness develops (NICE, 2026a).

The purpose of vitamin K prophylaxis is therefore prevention. It does not treat an existing feeding problem, tongue-tie or other newborn condition; it reduces the likelihood that a baby will develop bleeding as a result of vitamin K deficiency.

NICE recommends that vitamin K prophylaxis is offered to newborn babies because vitamin K deficiency bleeding, although rare, can have serious consequences (NICE, 2026a).

How is vitamin K administered?

In the UK, vitamin K can be administered by intramuscular injection or orally. NICE recommends that parents should be offered vitamin K prophylaxis and explains that intramuscular administration is the most effective method. Where parents do not want their baby to receive an injection, oral vitamin K should be offered as an alternative (NICE, 2026a).

Vitamin K by injection

The intramuscular injection is generally given into the baby's thigh. A single dose provides a reliable source of vitamin K during the period when the baby is most vulnerable to deficiency.

As with any injection, there can be brief discomfort and local effects such as soreness or bruising. These considerations can form part of the discussion with families when they are deciding which route they prefer.

Vitamin K by mouth

Oral vitamin K provides an alternative for families who do not want their baby to receive an intramuscular injection. The important difference is that oral administration involves a course of doses rather than relying on a single injection.

The exact preparation and dosing schedule should be provided by the maternity or neonatal service and followed according to the manufacturer's instructions. NICE advises that families choosing oral vitamin K should understand that several doses may be required, including doses after the baby has left hospital (NICE, 2026a).

This means that an oral course is dependent on the recommended doses actually being received. If a dose is missed, vomited or otherwise not given, the family should seek advice from the healthcare professional responsible for the baby's care about what should happen next rather than assuming that the course remains complete.

The route of administration is also considered in the context of the individual baby. Prematurity, illness and other clinical circumstances may affect which option is most appropriate.

What if a family initially declines vitamin K?

Parents and legal caregivers should be able to make an informed decision about vitamin K after being given appropriate information about its purpose, benefits and limitations. A decision to decline vitamin K should not prevent a family from accessing other healthcare or from asking questions and revisiting the decision.

Some families may initially decline vitamin K but later decide that they would like their baby to receive it. In that situation, the appropriate next step is to contact the maternity service, neonatal team, GP, health visitor or another appropriate NHS healthcare professional so that the baby's age, health, previous doses and the available preparation can be taken into account.

There is not one universal catch-up approach that can simply be applied to every baby who initially declined prophylaxis. The appropriate regimen depends on the individual circumstances, so families should obtain advice from the service responsible for the baby's care rather than relying on a general schedule found online.

This is an area where informed choice is particularly important. Dr Sara Wickham has written extensively about vitamin K, including the evidence surrounding prophylaxis, the distinction between relative and absolute risk, and what families who decline vitamin K should know (Wickham, 2026a; Wickham, 2026b). Her work provides additional discussion for families who want to explore the evidence and uncertainties surrounding the decision.

What if an oral course was started but not completed?

An incomplete oral course needs to be distinguished from a completed course of oral prophylaxis.

If one or more doses have been missed, the appropriate response depends on the baby's age, the preparation used, which doses were received and the baby's wider health circumstances. Families should therefore contact the relevant maternity, neonatal or medical service for advice.

This distinction can become particularly important if the baby subsequently requires an invasive procedure. Knowing that “vitamin K was given” is not necessarily enough information; the route, timing and completion of an oral course may all be relevant when considering the baby's current circumstances.

Vitamin K and clinical procedures

Vitamin K status can become particularly relevant when an infant is being considered for an invasive or surgical procedure.

Frenulotomy involves division of the lingual frenulum and is a regulated surgical procedure in its own right. Although the area being divided is small, tissue containing blood vessels is being cut and bleeding is a recognised potential complication.

A small amount of bleeding may occur following frenulotomy and will generally be managed as part of the procedure and its immediate aftercare. More significant bleeding is uncommon, but it is one of the risks that should be considered when assessing whether a procedure is appropriate.

For this reason, vitamin K status may form part of the clinical assessment before an elective procedure. This may include establishing whether vitamin K was given, whether it was administered intramuscularly or orally, whether an oral course was completed and whether there are other factors that could affect bleeding risk.

The absence of vitamin K prophylaxis does not automatically mean that an elective procedure can never take place. Equally, a clinician or service may determine that it is not appropriate to proceed until the individual bleeding risk has been assessed more fully.

This is an important distinction. A decision to postpone or decline an elective procedure because the bleeding risk cannot be adequately assessed is a clinical safety decision. It should not be presented as a judgement about the family for having made a particular decision regarding vitamin K.

What else might affect bleeding risk?

Vitamin K status is only one part of an assessment.

A baby's medical history may identify additional circumstances that warrant consideration before an invasive procedure. These can include prematurity, significant illness, a known liver condition, conditions affecting bile flow or vitamin absorption, unexplained or unusual bruising or bleeding, or a family history of a diagnosed bleeding disorder.

The liver is particularly relevant because it is responsible for producing the vitamin-K-dependent clotting factors. Conditions affecting liver function can therefore have implications for haemostasis independently of whether vitamin K prophylaxis was given.

Conditions affecting bile flow can also be relevant because vitamin K is fat-soluble and its absorption depends partly on normal fat digestion and bile delivery to the intestine. Persistent pale or unusually light stools, particularly when accompanied by jaundice or dark urine, require medical assessment because they can be signs of cholestasis or another underlying condition. This is not simply a question of whether the baby has “bowel problems”, and such symptoms should not be attributed to vitamin K deficiency without appropriate assessment.

Where there is uncertainty about a baby's bleeding risk, medical review may be appropriate. In some circumstances, blood tests assessing clotting may form part of that assessment. The decision to investigate should be based on the individual baby and the clinical question rather than automatically applying the same testing to every baby who has not received vitamin K.

A normal screening result also does not exclude every possible bleeding disorder, so investigations should be interpreted alongside the baby's history and clinical presentation.

What should families know if vitamin K was declined?

Families who have decided not to give vitamin K should know what symptoms require medical attention, because the absence of prophylaxis means the baby remains at risk of VKDB.

Unexplained bleeding should be medically assessed rather than assumed to be part of normal newborn care. This may include persistent bleeding from the umbilical area, bleeding from the nose or mouth, blood in the urine, blood in vomit or stools, or unusual bruising.

More serious symptoms can include marked pallor, unusual sleepiness, difficulty waking, seizures or other signs that the baby is acutely unwell. Internal bleeding may not always be immediately visible, which is one reason why significant changes in a baby's behaviour or condition should not be dismissed.

Families should seek urgent medical attention if their baby appears seriously unwell or develops unexplained bleeding.

Vitamin K and feeding

Vitamin K is not a treatment for breastfeeding difficulties, bottle-feeding difficulties, milk transfer problems or tongue-tie.

There is a difference in vitamin K content between human milk and infant formula, with formula containing added vitamin K. This does not mean that one method of feeding should be considered preferable on the basis of vitamin K. Vitamin K prophylaxis is offered because newborn babies have relatively low vitamin K stores and can develop VKDB irrespective of how their feeding develops.

Feeding difficulties should therefore be assessed on their own merits. A baby who is struggling with breastfeeding, bottle feeding, expressing or combination feeding may have a range of contributing factors, and vitamin K status should not be used as an explanation for feeding symptoms.

Similarly, vitamin K does not determine whether a baby has a tongue-tie or whether frenulotomy is clinically appropriate. Decisions about tongue-tie should consider function, feeding history, observed feeding where appropriate, growth, comfort, previous support and the individual circumstances of the feeding dyad.

Vitamin K, choice and individual assessment

The decision about vitamin K belongs within the wider process of informed consent and individualised newborn care.

For some families, the decision will be straightforward. Others may want to understand more about the evidence, the difference between injection and oral administration, or what declining prophylaxis means. A family may also make one decision immediately after birth and reconsider it later as circumstances or understanding change.

Respecting informed choice does not remove the responsibility of healthcare professionals to explain relevant risks, nor does it require a practitioner undertaking an elective procedure to ignore an unresolved bleeding risk.

Where vitamin K has been declined, where an oral course is incomplete, or where records cannot confirm what was administered, the appropriate response before an elective procedure may therefore be an individual assessment of the baby's bleeding risk. Depending on the circumstances, this may involve obtaining further clinical information, seeking medical advice or considering investigations such as coagulation screening.

For frenulotomy, this forms only one part of the overall assessment. The reason for considering the procedure, the infant's oral function, feeding circumstances, potential benefits and limitations, alternatives and the family's informed decision all remain relevant.

Vitamin K is one part of newborn care, but understanding why it is offered, how it can be administered and what happens when prophylaxis is declined or incomplete allows families and healthcare professionals to approach the subject with greater clarity and without unnecessary assumptions.

References

National Institute for Health and Care Excellence (NICE) (2005) Division of ankyloglossia (tongue-tie) for breastfeeding. Interventional Procedures Guidance 149. London: NICE.

National Institute for Health and Care Excellence (NICE) (2026a) Postnatal care. NICE guideline NG194. London: NICE.

National Institute for Health and Care Excellence (NICE) (2026b) Intrapartum care. NICE guideline NG235. London: NICE.

O'Shea, J.E., Foster, J.P., O'Donnell, C.P.F., Breathnach, D., Jacobs, S.E., Todd, D.A. and Davis, P.G. (2017) 'Frenotomy for tongue-tie in newborn infants', Cochrane Database of Systematic Reviews, 3, CD011065.

Puckett, R.M. and Offringa, M. (2000) 'Prophylactic vitamin K for vitamin K deficiency bleeding in neonates', Cochrane Database of Systematic Reviews, 4, CD002776.

Watson, R., McNinch, A., Gillbertson, C. et al. (2011) 'Guidelines on the administration of vitamin K to newborn infants', British Journal of Haematology, 154(1), pp. 8–17.

Wickham, S. (2026a) 'Five things parents should know if they decide to decline vitamin K'. Sara Wickham.

Wickham, S. (2026b) 'Vitamin K: evidence, risk and informed choice'. Sara Wickham.