Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
More evidence is needed to rate the effectiveness of vitamin K for these uses.
How does it work?
Vitamin K is an essential vitamin that is needed by the body for blood clotting and other important processes.
Are there safety concerns?
- Vitamin K is safe for most people. Most people do not experience any side effects when taking in the recommended amount each day.
Special precautions & warnings:
- Pregnancy and breast-feeding: When taken in the recommended amount each day, vitamin K is considered safe for pregnant and breast-feeding women, but don't use higher amounts without the advice of your healthcare professional.
- Kidney disease: Too much vitamin K can be harmful if you are receiving dialysis treatments due to kidney disease.
- Liver disease: Vitamin K is not effective for treating clotting problems caused by severe liver disease. In fact, high doses of vitamin K can make clotting problems worse in these people.
Are there interactions with medications?
Major
Do not take this combination.
Warfarin (Coumadin)
- Vitamin K is used by the body to help blood clot. Warfarin (Coumadin) is used to slow blood clotting. By helping the blood clot, vitamin K might decrease the effectiveness of warfarin (Coumadin). Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.
Are there interactions with herbs and supplements?
Coenzyme Q-10
- Coenzyme Q-10 is chemically similar to vitamin K and, like vitamin K, can promote blood clotting. Using these two products together can promote blood clotting more than using just one. This combination can be a problem for people who are taking warfarin to slow blood clotting. Coenzyme Q-10 plus vitamin K might overwhelm the effects of warfarin and could allow the blood to clot.
Tiratricol
- There is a concern that tiratricol might interfere with vitamin K's role in blood clotting.
Vitamin A
- In animals, high doses of vitamin A interfere with vitamin K's ability to clot blood. But it's not known if this also happens in people.
Vitamin E
- High doses of vitamin E (e.g. greater than 800 units/day) can make vitamin K less effective in clotting blood. In people who are taking warfarin to keep their blood from clotting, or in people who have low vitamin K intakes, high doses of vitamin E can increase the risk of bleeding.
Are there interactions with foods?
There are no known interactions with foods.
What dose is used?
The following doses have been studied in scientific research:
BY MOUTH:
For bleeding disorders such as hypoprothrombinemia: 2.5-25 mg of vitamin K1 (phytonadione).
For counteracting bleeding that can occur when too much of the anticoagulant warfarin is given: 1-5 mg of vitamin K is typically used; however, the exact dose needed is determined by a lab test called the INR.
There isn't enough scientific information to determine recommended dietary allowances (RDAs) for vitamin K, so daily adequate intake (AI) recommendations have been formed instead: The AIs are: infants 0-6 months, 2 mcg; infants 6-12 months, 2.5 mcg; children 1-3 years, 30 mcg; children 4-8 years, 55 mcg; children 9-13 years, 60 mcg; adolescents 14-18 years (including those who are pregnant or breast-feeding), 75 mcg; men over 19 years, 120 mcg; women over 19 years (including those who are pregnant and breast-feeding), 90 mcg.
Other names
4-Amino-2-Methyl-1-Naphthol, Fat-Soluble Vitamin, Menadiol Acetate, Menadiol Sodium Phosphate, Menadione, Menadione Sodium Bisulfite, Menaquinone, Menatetrenone, Phytonadione, Methylphytyl Naphthoquinone, Phylloquinone, Phytomenadione, Vitamina K, Vitamine K.