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Is vitamin K safe for kids and teens?

Written by the Full Measure editorial team, which sells supplements. Approved for publication by the Full Measure owners. Updated .

Drafted with AI assistance from the sources listed below. How we write these

Quick answer

NIH lists adequate vitamin K intakes of 30 to 75 mcg a day for ages 1 to 18, rising with age, and sets no upper limit because no adverse effects have been reported. Ask your doctor before giving a child a supplement, and first if a child takes a blood thinner.1,2

Key facts

  • NIH's adequate intakes are 2 mcg a day at birth to 6 months, 2.5 mcg at 7 to 12 months, 30 mcg at ages 1 to 3, 55 mcg at 4 to 8, 60 mcg at 9 to 13 and 75 mcg at 14 to 18.1,2
  • NIH sets no upper limit for vitamin K, because the expert panel found no adverse effects from food or supplements in people or animals. This does not apply to anyone taking warfarin.1
  • Among children and teens aged 2 to 19, average vitamin K intake from food is 66 mcg a day, NIH reports from 2011 to 2012 survey data.1
  • Menadione, sometimes called vitamin K3, damaged liver cells in laboratory studies and is no longer used in dietary supplements or fortified foods.1
  • The American Academy of Pediatrics recommends a single shot of 0.5 to 1 mg of vitamin K1 for every newborn.1

Adequate intakes and the upper limit by age

NIH adequate intakes of vitamin K for children and teens1,2
AgeAdequate intake per dayUpper limit
Birth to 6 months2.0 mcgNone set
7 to 12 months2.5 mcgNone set
1 to 3 years30 mcgNone set
4 to 8 years55 mcgNone set
9 to 13 years60 mcgNone set
14 to 18 years75 mcgNone set

NIH's infant figures assume that every newborn receives the vitamin K injection at birth. The expert panel set no upper limit at any age because of vitamin K's low potential for harm.1

No upper limit has been set for vitamin K, because of its low potential for harm: the expert panel that sets intakes found no reported adverse effects from vitamin K in food or supplements in people or animals. This does not apply to anyone taking warfarin or a similar blood thinner.1,2

What children and teens get from food

NIH reports that among children and teens aged 2 to 19, average vitamin K intake from foods in 2011 to 2012 survey data was 66 mcg a day. Green leafy vegetables, vegetable oils, some fruit, meat, cheese, eggs and soybeans supply it, and bacteria in the colon make some more. NIH says most people in the United States get enough from the foods they eat.1,2

Forms used in supplements

Vitamin K supplements come as K1 (phylloquinone or phytonadione) and K2 (menaquinone-4 and menaquinone-7). A synthetic form, menadione or K3, damaged liver cells in laboratory studies in the 1980s and 1990s and is no longer used in supplements or fortified foods. The sources checked do not report trials of vitamin K supplements in children or teens, which is not a finding either way.1,2

The newborn shot

NIH's health professional sheet says the American Academy of Pediatrics recommends a single intramuscular dose of 0.5 to 1 mg of vitamin K1 at birth to prevent vitamin K deficiency bleeding, because little vitamin K crosses the placenta and breast milk is low in it. Ask your baby's pediatrician about the shot.1

Little vitamin K crosses the placenta and breast milk is low in it, so newborns have little at birth. The American Academy of Pediatrics recommends a single shot of 0.5 to 1 mg of vitamin K1 for every newborn.1

Who should ask their doctor

Ask your doctor before giving a child or teen a vitamin K supplement, as NIH advises for any supplement given to a child. Ask first if the child takes warfarin or a related blood thinner, is on a long course of antibiotics, or has cystic fibrosis, celiac disease, ulcerative colitis or short bowel syndrome, which NIH says can lower how much vitamin K the body absorbs.1,2,3

Questions people ask

Is vitamin K good for teens?

This page is about safety. NIH says most people in the United States get enough vitamin K from food, that a shortage is very rare, and it lists 75 mcg a day as adequate at ages 14 to 18. A doctor can say whether a teen needs a supplement.1,2

Is vitamin K safe for kids?

NIH sets no upper limit because no adverse effects have been reported from food or supplements, with an exception for anyone taking warfarin. The sources checked have no trial of supplements in children, so ask your doctor.1

Is vitamin K ok for kids who take medicines?

NIH says vitamin K can interact seriously with warfarin and that antibiotics, bile acid sequestrants and orlistat can lower vitamin K. Ask your doctor or pharmacist about any medicine a child takes.2

Why is vitamin K good for teenagers?

NIH describes vitamin K as a nutrient the body needs and gives 75 mcg a day as the adequate intake for ages 14 to 18. This page does not make claims about benefits, so see the guide for graded evidence.1,2

Is a vitamin K supplement for teens needed?

NIH says severe deficiency is very rare and that most people get enough from food, and it names newborns without the injection and people with absorption problems as at-risk groups. Ask your doctor about a particular teen.1,2

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Sources

  1. National Institutes of Health, Office of Dietary Supplements. Vitamin K: Fact Sheet for Health Professionals. Updated March 29, 2021. Opened 2026-10-07.
  2. Office of Dietary Supplements, National Institutes of Health. Vitamin K: Fact Sheet for Consumers. Updated March 22, 2021. Opened 2026-10-07.
  3. National Institutes of Health, Office of Dietary Supplements. Dietary Supplements: What You Need To Know. Fact sheet for consumers. Updated January 4, 2023. Opened 2026-10-07.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.