Vitamin K is a nutrient that aids in normal blood clotting or coagulation. Healthy men and women should get at least 120 mcg or 90 mcg, respectively, of vitamin K daily. Although the naturally occurring bacteria in your digestive tract produce vitamin K, you also may increase your vitamin K intake by consuming foods rich in this nutrient or by taking a supplemental form of vitamin K. Be sure to talk with your medical provider about the possible risks associated with vitamin K before beginning treatment with this supplement.
Side Effects
There are three forms of vitamin K: vitamin K1, also called phylloquinone; vitamin K2, also called menaquinone; and vitamin K3, also called menadione or menaphthone. People who take vitamin K1 typically don't experience noticeable side effects. Treatment with vitamin K3 injections, however, may result in adverse side effects, the American Cancer Society warns. Vitamin K3 side effects include chest pain, shortness of breath, flushing and numbness in your legs and arms. Certain people also may experience an allergic reaction shortly after receiving a vitamin K3 injection. Allergic reactions may be mild to severe and include hives, breathing problems, difficulty swallowing, weakness and pale skin. Severe allergic reactions require emergency medical care to limit the development of potentially life-threatening complications, such as shock.
Medication Interactions
Discuss all medications you are taking with your physician before you begin taking any new drug or supplement, including vitamin K. The University of Maryland Medical Center warns that vitamin K supplements may significantly reduce the efficacy of blood-thinning medications, such as warfarin. Additionally, your body may have difficulty absorbing vitamin K if you also are taking phenytoin, orlistat and certain antibiotics.
Nutrient Interactions
Nutritional supplements also may interact with vitamin K and may increase your risk of developing side effects. Linus Pauling Institute reports that concomitant treatment with large doses of vitamin A and vitamin K may make it harder for your body to absorb vitamin K. Additionally, treatment with vitamin E in conjunction with vitamin K may elevate your risk of experiencing bleeding complications, especially if you are also taking a blood thinner.
Contraindications
The safety of vitamin K treatment during pregnancy is not yet known, as of January 2011. Consequently, women who are pregnant or breastfeeding should avoid taking this supplement unless otherwise instructed by a medical professional. Expectant mothers who are taking antiseizure medications may require treatment with vitamin K supplements about 2 to 4 weeks prior to giving birth to reduce the risk of fetal bleeding complications, the American Cancer Society explains. If you are allergic to vitamin K, do not take this supplement. Improper use of vitamin K by hypersensitive people may induce a severe and potentially life-threatening allergic reaction.
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