Vitamin K shots are a routine part of newborn care in many countries, including the United States. They've been given to newborns for more than 60 years and show no evidence of harm to the baby.
Despite the proven safety and effectiveness of vitamin K vaccines, some parents have concerns or misconceptions. Our team of experts break down the facts and myths on this life-saving treatment.
What is vitamin K and why is it important?
Vitamin K is a nutrient essential for blood clotting. It's found in food and produced by healthy gut bacteria. However, newborns have very low levels of vitamin K because:
- Very little is transferred across the placenta from the mother during pregnancy.
- Breast milk and formula contain minimal vitamin K. Recent studies show that mothers who take high doses of vitamin K while breastfeeding don't increase the level of vitamin K passed to the baby, according to the American Academy of Pediatrics.
- Babies don't start producing their own vitamin K until they begin eating solid foods at around 6 months.
Without enough vitamin K, newborns are at risk for vitamin K deficiency bleeding (VKDB). This is also known as hemorrhagic disease of the newborn.
UC Davis Health providers have treated infants for VKDB in our Emergency Department, as it's the only level 1 pediatric trauma center serving inland Northern California. This life-threatening condition could have been prevented with a vitamin K injection at birth.
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Fact: The vitamin K shot prevents VKDB.
The vitamin K injection given at birth:
- Provides immediate protection.
- Builds up stores of vitamin K to have until the baby can produce their own vitamin K.
- Is safe and effective in preventing all forms of VKDB:
- Early onset (first day of life)
- Classical (days 2–7)
- Late onset (up to 6 months)
VKDB can cause serious complications like bleeding in the brain, under the scalp, or in the gastrointestinal (GI) tract. This can potentially lead to lifelong disability or death.
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Myth: Oral vitamin K works just as well as the vitamin K shot.
While oral vitamin K is used in some countries, it's less reliable because:
- It requires multiple doses over weeks or months.
- It's easy to forget or miss doses.
- There is no FDA-approved oral form in the U.S.
- Available liquid forms may have unregulated doses and additives.
- Cases of VKDB still occur with oral regimens.
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Myth: Vitamin K shots cause cancer.
A 1990 British Medical Journal study raised concerns about a possible link between vitamin K injections and childhood cancer. However:
- Numerous follow-up studies have not found any association.
- The original findings have not been replicated.
- The medical consensus is that vitamin K injections are safe.
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Fact: Side effects of the vitamin K shot are minimal.
Severe allergic reactions (like anaphylaxis) to the vitamin K shot are extremely rare. Mild irritation at the injection site has been reported.
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This blog was medically reviewed by pediatric trauma surgeon Jonathan Kohler and pediatrician Lena van der List.
