Vitamin K interactions
Vitamin K (in supplements and leafy greens) directly counteracts warfarin, so a steady intake matters more than avoiding it.
Vitamin K has 30 documented interactions across the FDA labels and fact sheets we index: 7 major, 20 moderate, 3 minor, and 0 where a label reports no significant interaction. Each entry below quotes the sentence behind it. This vitamin and mineral page is a starting point, not a verdict for your situation.
Interactions from the label
Major interactions (7)
Patients with a hemorrhagic diathesis (e.g., hemophilia, hypoprothrombinemia, von Willebrand's disease, the thrombocytopenias, thrombasthenia and other ill-defined hereditary platelet dysfunctions, severe vitamin K deficiency and severe liver damage). (Butalbital, aspirin, and caffeine label, Contraindications)
WARNING: SERIOUS ADVERSE REACTIONS OR DEATH IN PATIENTS WITH COMPLETE DPD DEFICIENCY and INCREASED RISK OF BLEEDING WITH CONCOMITANT USE OF VITAMIN K ANTAGONISTS Increased risk of serious adverse reactions or death in patients with complete DPD deficiency • Test patients for genetic variants of DPYD prior to initiating XELODA unless immediate treatment is necessary. (Capecitabine label, Boxed warning)
Do not administer agents that enhance the risk of hemorrhage with fondaparinux sodium unless essential for the management of the underlying condition, such as vitamin K antagonists for the treatment of VTE. (Fondaparinux label, Warnings and precautions)
A potentially life-threatening bleeding disorder related to decreased levels of vitamin K-dependent clotting factors may occur in newborns exposed to phenytoin in utero. (Fosphenytoin label, Warnings and precautions)
A potentially life-threatening bleeding disorder related to decreased levels of vitamin K-dependent clotting factors may occur in newborns exposed to phenytoin in utero. (Phenytoin label, Warnings and precautions)
Postmarketing reports suggest that concomitant administration of high doses of cefazolin and rifampin may prolong the prothrombin time, leading to severe vitamin K–dependent coagulation disorders that may be life-threatening or fatal. (Rifampin label, Warnings)
Vitamin K reduces the anticoagulant effect of warfarin; sudden changes in intake from supplements or diet can throw off INR. (NIH Office of Dietary Supplements, Vitamin K)
Moderate interactions (20)
For patients with APS (especially those who are triple positive [positive for lupus anticoagulant, anticardiolipin, and anti-beta 2-glycoprotein I antibodies]), treatment with DOACs has been associated with increased rates of recurrent thrombotic events compared with vitamin K antagonist therapy. (Apixaban label, Warnings and precautions)
Some patients had serious bleeding including intracranial, retroperitoneal, and gastrointestinal requiring blood transfusion and/or administration of vitamin K. (Bicalutamide label, Warnings and precautions)
This can adversely affect patients with inherited (i.e. hemophilia) or acquired (i.e. liver disease or vitamin K deficiency) bleeding disorders. (Butalbital, aspirin, caffeine, and codeine label, Warnings and precautions)
Prothrombin time should be monitored in patients at risk and exogenous vitamin K administered as indicated (5.5) (Cefazolin label, Warnings and precautions)
Prothrombin time should be monitored in patients at risk, and exogenous vitamin K administered as indicated. (Cefepime label, Warnings and precautions)
Prothrombin time should be monitored in patients at risk and exogenous vitamin K administered as indicated. (Cefixime label, Warnings and precautions)
Prothrombin time should be monitored and exogenous vitamin K administered as indicated. (Cefotetan label, Warnings)
Patients with impaired vitamin K synthesis or low vitamin K stores (e.g., chronic hepatic disease and malnutrition) may require monitoring of prothrombin time during Ceftriaxone for Injection and Dextrose Injection treatment. (Ceftriaxone label, Warnings and precautions)
Vitamin K or Fat-Soluble Vitamin Deficiencies: Colesevelam hydrochloride may decrease absorption of fat-soluble vitamins. (Colesevelam label, Warnings and precautions)
For patients with APS (especially those who are triple-positive [positive for lupus anticoagulant, anticardiolipin, and anti-beta 2-glycoprotein I antibodies]), treatment with DOACs has been associated with increased rates of recurrent thrombotic events compared with vitamin K antagonist therapy. (Dabigatran label, Warnings and precautions)
For patients with APS (especially those who are triple positive [positive for lupus anticoagulant, anticardiolipin antibodies, and anti-beta 2-glycoprotein I antibodies]), treatment with DOACs has been associated with increased rates of recurrent thrombotic events compared with vitamin K antagonist therapy. (Edoxaban label, Warnings and precautions)
Drug Interactions Oral Anticoagulants — Thyroid hormones appear to increase catabolism of vitamin K-dependent clotting factors. (Levothyroxine and liothyronine label, Drug interactions)
Drug Interactions Anticoagulants (oral): Due to potential inhibition of vitamin K activity by methimazole, the activity of oral anticoagulants (e.g., warfarin) may be increased; additional monitoring of PT/INR should be considered, especially before surgical procedures. β-adrenergic blocking agents: Hyperthyroidism may cause an increased clearance of beta blockers… (Methimazole label, Drug interactions)
Oral neomycin sulfate may enhance the effect of coumarin in anticoagulants by decreasing vitamin K availability. (Neomycin label, Drug interactions)
- OrlistatModerate
The effect of ORLISTAT on the absorption of supplemental vitamin D, vitamin A, and nutritionally-derived vitamin K is not known at this time [see Clinical Pharmacology (12.3) , and Warnings and Precautions (5.1) ] . (Orlistat label, Drug interactions)
Increased prothrombin time has been reported in patients concomitantly treated with pentoxifylline and vitamin K antagonists. (Pentoxifylline label, Drug interactions)
Drug Interactions Anticoagulants (oral) : Due to the potential inhibition of vitamin K activity by propylthiouracil, the activity of oral anticoagulants (e.g., warfarin) may be increased; additional monitoring of PT/INR should be considered, especially before surgical procedures. (Propylthiouracil label, Drug interactions)
Warfarin and oral anticoagulants Cinchona alkaloids, including quinine, may have the potential to depress hepatic enzyme synthesis of vitamin K-dependent coagulation pathway proteins and may enhance the action of warfarin and other oral anticoagulants. (Quinine label, Drug interactions)
For patients with APS (especially those who are triple positive [positive for lupus anticoagulant, anticardiolipin, and anti-beta 2-glycoprotein I antibodies]), treatment with DOACs has been associated with increased rates of recurrent thrombotic events compared with vitamin K antagonist therapy. (Rivaroxaban label, Warnings and precautions)
- SugammadexModerate
In vitro experiments demonstrated additional aPTT and PT(INR) prolongations for sugammadex in combination with vitamin K antagonists, unfractionated heparin, low molecular weight heparinoids, rivaroxaban, and dabigatran up to ~25% and ~50% at C max levels of sugammadex corresponding to 4 mg/kg and 16 mg/kg doses, respectively. (Sugammadex label, Warnings and precautions)
Minor mentions (3)
Methylergonovine maleate has been administered instead of vitamin K and Hepatitis B vaccine, medications which are routinely administered to the newborn. (Methylergonovine label, Warnings)
Cutaneous Reactions Parenteral administration of vitamin K replacements (including phytonadione injectable emulsion) may cause cutaneous reactions. (Phytonadione (vitamin K1) label, Warnings and precautions)
Neonatal hemorrhage, with a coagulation defect resembling vitamin K deficiency, has been described in newborns whose mothers were taking primidone and other anticonvulsants. (Primidone label, Warnings)
Check Vitamin K against everything you take. Add your full list; every pair is checked at once.
Open in the checkerNot medical advice. Severity reflects the label's wording, not your circumstances. A "major" flag can be routine under supervision and a "minor" one can matter at high doses. Ask a pharmacist.