Health Guide

Vitamin K

What is it?

Vitamin K is a fat soluble vitamin used in the treatment of vitamin K deficiency caused by broad-spectrum antibiotics (used to treat infection), cephalosporins (used to treat infection), and prednisone (steroid). It is also supplemented in combination with other vitamins when malabsorption (decreased inability to absorb vitamins, mineral, and nutrients from food) is present. vitamin K is given, under the supervision of a doctor, to newborn babies to prevent hemorrhage (bleeding) and to patients on blood thinning medicine whose blood has become too thin. Vitamin K has also been used in the prevention and treatment of osteoporosis (brittle bones). Vitamin K1 (phylloquinone) is found naturally in leafy green vegetables (broccoli, brussel sprouts, cabbage, kale, lettuce, parsley, spinach, turnip greens, and water cress), cauliflower, and the vegetable oils from soybean, cottonseed, canola, and olive. Bacteria present in the human bowel produce vitamin K2.

Other names for vitamin K include: Vitamin K1 or Phylloquinone, Phytonadione, and Phytomenadione; Vitamin K2 or Menatetrenone; Vitamin K3 or Menadione.

Ask your doctor, nurse, or pharmacist if you need more information about this medicine or if any information in this leaflet concerns you.

Before Using:

Tell your doctor if you

  • are taking medicine or are allergic to any medicine (prescription or over-the-counter (OTC) or dietary supplement)
  • are pregnant or plan to become pregnant while using this medicine
  • are breastfeeding
  • have any other health problems, such as high blood pressure or heart or blood vessel disease


Talk with your caregiver about how much vitamin K you should take. The amount depends on the strength of the medicine and the reason you are taking Vitamin K. If you are using this medicine without instructions from your caregiver, follow the directions on the medicine bottle. Do not take more medicine or take it more often than the directions tell you to.

To store this medicine:

Keep all medicine locked up and away from children. Store medicine away from heat and direct light. Do not store your medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down and not work the way it should work. Throw away medicine that is out of date or that you do not need. Never share your medicine with others.

Drug and Food Interactions:

Do not take vitamin K without talking to your doctor first if you are taking:

  • Blood thinning medicine (examples: abciximab (ReoPro(R)), aspirin (Bufferin(R), Ecotrin(R)), clopidogrel (Plavix(R)), tinzaparin (Innohep(R)), warfarin (Coumadin(R))) (18,19)
  • Leafy green vegetables (examples: broccoli, brussel sprouts, cabbage, lettuce, parsley, spinach), cauliflower, vegetable oils from soybean, cottonseed, canola, and olive (20)
  • Olestra (Olean, non-fat cooking oil) (16)
  • Pau d'arco (herbal supplement used for infections or skin problems) (21)


  • Before taking vitamin K, tell your doctor if you are pregnant or breastfeeding
  • If you have kidney problems or dehydration, you should not take potassium without first consulting your health care professional (1)

Side Effects:

Call your doctor right away if you have any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hand, swelling or tingling in your mouth or throat, chest tightness, trouble breathing, or rash
  • Back, leg, or stomach pains, bleeding gums, fever, headache, nausea or vomiting (7)
  • Severe allergic reactions following intravenous administration (medicine that is put directly into your body through one of your veins) of vitamin K (10,11)

Other Side Effects:

You may have the following side effects, but this medicine may also cause other side effects. Tell your doctor if you have side effects that you think are caused by this medicine.

  • Change in sense of taste (17)
  • Flushing, sweating (17)
  • Pain, swelling, or tenderness where the shot was given (8,9)


1. Cracium AM, Wolf J, Knapen MHJ et al: Improved bone metabolism in female elite athletes after vitamin K supplementation. Int J Sport Med 1998; 19:479-484.

2. Yaguchi M, Miyazawa K, Otawa M et al: Vitamin K2 therapy for a patient with myelodysplastic syndrome. Leukemia 1999; 13(1):144-145.

3. Knapen MHJ, Hamulyak K & Vermeer C: The effect of vitamin K supplementation on circulating osteocalcin (bone Gla protein) and urinary calcium excretion. Ann Intern Med 1989; 111:1001-1005.

4. Iwamoto I, Kosha S, Noguchi S et al: A longitudinal study of the effect of vitamin K2 on bone mineral density in postmenopausal women a comparative study with vitamin D3 and estrogen-progestin therapy. Maturitas 1999; 31(2):161-164.

5. Aisaka K, Uesato T, Miwa et al: Evaluation of vitamin K2 (menatetrenone) administration with hormone replacement therapy on prevention of osteoporosis in climacteric women. Ninth International Menopause Society World Congress on the Menopause, October 1999: 79-83.

6. Feskanich D, Weber P, Willett WC et al: Vitamin K intake and hip fractures in women: a prospective study. Am J Clin Nutr 1999; 69:74-79.

7. Zipursky A: Prevention of vitamin K deficiency bleeding in newborns. Br J Haematol 1999; 104:430-437.

8. Wong DA & Freeman S: Cutaneous allergic reaction to intramuscular vitamin K1. Aust J Dermatol 1999; 40:147-152.

9. Keough GC, English JC & Meffert JJ: Eczematous hypersensitivity from aqueous vitamin K injection. Cutis 1998; 61:81-83.

10. Corallo CE & Gillett M: Anaphylactic shock following intravenous vitamin K1. Aust J Hosp Pharm 1997; 27:146-147.

11. Aziz NA, Kamaruddin Z, Hassan Y et al: Vitamin K1-induced anaphylactic shock. J Pharm Technol 1996; 12:214-216.

12. Taylor JR & Wilt VM: Probable antagonism by green tea. Ann Pharmacother 1999; 33:426-428.

13. Lubetsky A, Dekel-Stern E, Chetrit A et al: Vitamin K intake and sensitivity to warfarin in patients consuming regular diets. Tromb Haemost 1999; 81:396-399.

14. Streif W, Andrew M, Marizinotto V et al: Analysis of warfarin therapy in pediatric patients: a prospective cohort study of 319 patients. Blood 1999; 94(9):3007-3014.

15. Block JB, Serpick AA, Miller W et al: Early clinical studies with lapachol (NSC-11905). Cancer Chemother Rep 1974; 4(4 part 2):27-28.

16. Harrell CC & Kline SS: Vitamin K-supplemented snacks containing olestra: implications for patients taking warfarin. JAMA 1999; 282(12):1133-1134.

17. Product Information: Mephyton(R), phytonadione (vitamin K1). Merck & Co., Inc., Whitehouse Station, NJ, 2004.

18. Karlson B, Leijd B & Hellstrom K: On the influence of vitamin K-rich vegetables and wine on the effectiveness of warfarin treatment. Acta Med Scand 1986; 220:347-350.

19. Kudo T: Warfarin antagonism of NATTO and increase in serum vitamin K by intake of NATTO. Artery 1990; 17:189-201.

20. Booth SL & Suttie JW: Dietary intake and adequacy of vitamin K. J Nutr 1998; 128:785-788.

21. Dinnen RD & Ebisuzaki K: The search for novel anticancer agents: a differentiation-based assay and analysis of a folklore product. Anticancer Res 1997; 17:1027-1034.

Last Updated: 5/4/2018
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites.

All rights reserved