Vitamin K1 Phytonadione

Reviewed on 11/1/2021

What Is Vitamin K1 (Phytonadione) and How Does It Work?

Vitamin K1 (Phytonadione) is a prescription medication used as Nutritional Supplementation, and to treat symptoms of Hypoprothrombinemia due to drugs or factors limiting absorption or synthesis, and Reversal of Warfarin Effects.

What Are Dosages of Vitamin K1 (Phytonadione)?

Adult and Pediatric dosage


  • 100mcg
  • 5mg

Injection emulsion

  • 2mg/mL
  • 10mg/mL

Nutritional Supplementation

Adult dosage

Recommended daily intake (RDA): 

  • Males: 120 mcg per day orally
  • Females: 90 mcg per day orally

Pediatric dosage

  • Children 0-6 months: 2mcg per day
  • Children 6-12 months: 2.5 mcg/day
  • Children 1-3 years: 30 mcg/day
  • Children 4-8 years: 55 mcg/day
  • Children 9-13 years: 60 mcg/day
  • Children 14-18 years: 75 mcg/day

Hypoprothrombinemia Due to Drugs or Factors Limiting Absorption or Synthesis

  • 2.5-10 mg orally or subcutaneous; may be increased as needed to 25 mg or, rarely, to 50 mg; maybe repeated in 12-48 hours

Reversal of Warfarin Effects

  • Omit 1-2 doses, or hold warfarin; monitor INR and adjust warfarin dose accordingly
  • INR 4.5-10, no bleeding: 2012 ACCP guidelines suggest against routine use; 2008 ACCP guidelines suggest considering vitamin K1 (phytonadione) 1-2.5 mg orally once
  • INR greater than 10, no bleeding: 2012 ACCP guidelines recommend vitamin K1 PO (dose not specified); 2008 ACCP guidelines suggest 2.5-5 mg orally once; INR reduction observed within 24-48 hours, monitor INR and give additional vitamin K if needed
  • Minor bleeding, any elevated INR: Consider 2.5-5 mg orally once; may repeat if needed after 24 hours
  • Major bleeding, any elevated INR: 2012 ACCP guidelines recommend prothrombin complex concentrate, human (PCC, Kcentra) plus vitamin K1 5-10 mg IV (dilute in 50 mL IV fluid and infuse over 20 min)

NOTE: High vitamin K doses (ie, 10 mg or more) may cause warfarin resistance for a week or more; consider using heparin, LMWH, or direct thrombin inhibitors to provide adequate thrombosis prophylaxis in clinical conditions requiring chronic anticoagulation therapy (eg, atrial fibrillation)

Hemorrhagic Disease of the Newborn

  • Prophylaxis: 0.5-1 mg IM within 1 hour of birth
  • Treatment: 1 mg/dose/day SC; may require higher doses if mother has been receiving oral anticoagulant

Dosage Considerations – Should be Given as Follows: 

See "Dosages."


Next to red peppers, you can get the most vitamin C from ________________. See Answer

What Are Side Effects Associated with Using Vitamin K1 (Phytonadione)?

Common side effects of Vitamin K1 (Phytonadione) include:

  • dizziness,
  • flushing (warmth, redness, or tingly feeling), 
  • changes in the sense of taste, 
  • sweating, and
  • pain or swelling at the injection site

Serious side effects of Vitamin K1 (Phytonadione) include:

  • hives, 
  • difficulty breathing, 
  • swelling of the face, lips, tongue, or throat, 
  • weakness, 
  • tingling, 
  • lightheadedness
  • warmth, 
  • itching, 
  • chest pain, 
  • cold sweat
  • unusual or unpleasant taste in the mouth, 
  • blue colored lips, 
  • yellowing of the skin or eyes (jaundice), 
  • weak and rapid pulse, and
  • skin redness, itching, or a hard lump at the injection site

Rare side effects of Vitamin K1 (Phytonadione) include:

  • none 
This is not a complete list of side effects and other serious side effects or health problems may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Vitamin K1 (Phytonadione)?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them.  Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first

  • Vitamin K1 (Phytonadione) has severe interactions with no other drugs. 
  • Vitamin K1 (Phytonadione) has serious interactions with the following drugs:
    • warfarin
  • Vitamin K1 (Phytonadione) has moderate interactions with at least 39 other drugs.
  • Vitamin K1 (Phytonadione) has minor interactions with the following drugs:

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drugs interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use.  Keep a list of all your medications with you, and share this information with your doctor and pharmacist.  Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

What Are Warnings and Precautions for Vitamin K1 (Phytonadione)?


  • Hypersensitivity

Effects of drug abuse

  • None

Short-Term Effects

  • See “What are Side Effects Associated with Using Vitamin K1 (Phytonadione)?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Vitamin K1 (Phytonadione)?”


  • Rapid IV administration may cause potentially fatal anaphylaxis
  • Protect from light; agent is rapidly degraded
  • Avoid IM route if patients is bleeding or in 3rd trimester of pregnancy
  • Administer phtonadione to quickly lower INR into safe range in patients receiving vitamin K antagonists
  • Other forms of vitamin K (eg, menadione) are not effective in these settings; only vitamin K1 (ie, phytonadione) should be used
  • Time of onset depends on rate of synthesis of clotting factors
  • Potential for overcorrection
  • If initial doses do not reverse coagulopathy, higher doses are not likely to have any effect; ineffective in hereditary hypoprothrombinemia
  • Longer treatment durations (up to months) and much higher doses required in patients exposed to long-acting anticoagulant rodenticide
  • Hemolysis, hyperbilirubinemia, and jaundice reported in newborns treated with larger than recommended doses; use caution
  • Parenteral administration may cause cutaneous reactions; reactions have included eczematous reactions, scleroderma-like patches, urticaria, and delayed-type hypersensitivity reactions; time of onset ranged from 1 day to a year after parenteral administration; discontinue therapy for skin reactions and institute medical management
  • Serious adverse reactions including fatal reactions and “gasping syndrome” reported in premature neonates and infants in the intensive care unit who received drugs containing benzyl alcohol as a preservative; preterm, low-birth weight infants may be more likely to develop these reactions because they may be less able to metabolize benzyl alcohol; preterm, low-birth weight infants may be more likely to develop these reactions because they may be less able to metabolize benzyl alcohol; use benzyl alcohol-free formulations in neonates and infants, if available
  • Drug interaction overview
  • Anticoagulants
    • Mephyton may induce temporary resistance to prothrombin-depressing anticoagulants, especially when larger doses of the drug are used; should this occur, higher doses of anticoagulant therapy may be needed when resuming anticoagulant therapy, or a change in therapy to a different class of anticoagulant may be necessary (ie, heparin sodium)
    • The drug does not affect anticoagulant actions of heparin

Pregnancy and Lactation

  • The drug formulation contains benzyl alcohol, which has been associated with gasping syndrome in neonates; the preservative benzyl alcohol can cause serious adverse events and death when administered intravenously to neonates and infants; if therapy is needed during pregnancy, consider using a benzyl alcohol-free formulation; published studies with the use of phytonadione during pregnancy have not reported a clear association with phytonadione and adverse developmental outcomes; there are maternal and fetal risks associated with vitamin K deficiency during pregnancy; animal reproduction studies have not been conducted with phytonadione
  • Pregnant women with vitamin K deficiency hypoprothrombinemia may be at an increased risk for bleeding diathesis during pregnancy and hemorrhagic events at delivery; subclinical maternal vitamin K deficiency during pregnancy has been implicated in rare cases of fetal intracranial hemorrhage
  • The drug formulation contains benzyl alcohol; if available, a Preservative-Free formulation is recommended when therapy is needed during lactation; phytonadione is present in breastmilk; there are no data on effects of therapy on the breastfed child or on milk production; the developmental and health benefits of breastfeeding should be considered along with the clinical need for therapy and any potential adverse effects on breastfed child from the drug or from the underlying maternal condition


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