Supplement·Interactions·Reviewed June 9, 2026
Vitamin K1 interactions.
Vitamin K1 has 19 documented interactions in the NutriStack database: 1 to avoid or watch closely, 13 that need timing or caution, and 5 that work synergistically. The full list, with what each pairing does, is below.
Vitamin K1 at a glance.
A quick, data-grounded summary. The full table is below.
Vitamin K1 has 19 documented interactions in the NutriStack database: 1 to avoid or watch closely, 13 that need timing or caution, and 5 that work synergistically. The full list, with what each pairing does, is below.
Everything that interacts with vitamin k1.
Every supplement and medication in the NutriStack database with a documented interaction with this substance, highest-severity first. Open any pair for the mechanism and sources.
| Substance | Interaction | What happens |
|---|---|---|
| Warfarin | Conflict | Vitamin K1 (phytonadione) directly reverses warfarin's anticoagulant effect. Even small, regular doses found in multivitamins (25 mcg/day) have been... details → |
| Ampicillin | Caution | Prolonged Ampicillin therapy can contribute to reduced vitamin K status in susceptible patients by altering gut flora, with higher concern in poor... |
| Cefixime | Caution | Prolonged Cefixime therapy can contribute to reduced vitamin K status in susceptible patients by altering gut flora, with higher concern in poor... |
| Cefpodoxime | Caution | Prolonged Cefpodoxime therapy can contribute to reduced vitamin K status in susceptible patients by altering gut flora, with higher concern in poor... |
| Cefuroxime | Caution | Prolonged Cefuroxime therapy can contribute to reduced vitamin K status in susceptible patients by altering gut flora, with higher concern in poor... |
| Chlorella | Caution | Stacking a vitamin K1 supplement on top of chlorella meaningfully increases total vitamin K1 exposure. For most healthy people this is simply... |
| Dicloxacillin | Caution | Prolonged Dicloxacillin therapy can contribute to reduced vitamin K status in susceptible patients by altering gut flora, with higher concern in... |
| Erythromycin | Caution | Prolonged Erythromycin therapy can contribute to reduced vitamin K status in susceptible patients by altering gut flora, with higher concern in poor... |
| Ginkgo Biloba | Caution | Ginkgo's antiplatelet activity can mildly counter vitamin K1's pro-coagulant role; relevant for warfarin patients managing INR through K1 intake. |
| Penicillin V Potassium | Caution | Prolonged Penicillin V Potassium therapy can contribute to reduced vitamin K status in susceptible patients by altering gut flora, with higher... |
| Rifampin | Caution | Rifampin can alter vitamin K dependent anticoagulation control and prolonged antibiotic therapy may affect vitamin K status. |
| Vitamin E | Caution | High-dose vitamin E (>400 IU) can antagonize vitamin K-dependent clotting factor activation, increasing bleeding risk. details → |
| Cholestyramine | Timing Sensitive | Cholestyramine can reduce vitamin K absorption and may increase bleeding risk or alter INR. |
| Icosapent Ethyl | Timing Sensitive | Icosapent ethyl is a fatty acid ester that requires dietary fat for absorption, and fat-soluble vitamin K1 is similarly best absorbed with a... |
| Evening Primrose Oil | Synergy | Evening Primrose Oil provides a fat-containing carrier that can improve absorption of fat-soluble compounds like Vitamin K1. |
| Flaxseed Oil | Synergy | Flaxseed Oil provides a fat-containing carrier that can improve absorption of fat-soluble compounds like Vitamin K1. |
| MCT Oil | Synergy | MCT Oil provides a fat-containing carrier that can improve absorption of fat-soluble compounds like Vitamin K1. |
| Vitamin K2 | Synergy | K1 primarily supports coagulation while K2 (MK-7) directs calcium to bones. Complementary roles in vitamin K metabolism. details → |
| Vitamin K2 MK-4 | Synergy | K1 primarily supports coagulation while K2 (MK-7) directs calcium to bones. Complementary roles in vitamin K metabolism. |
The full vitamin k1 profile.
Benefits, dosing by goal, forms, and the cited evidence for this supplement.
Common vitamin k1 questions.
Quick answers drawn from the table above.
What interacts with Vitamin K1?
In the NutriStack database, Vitamin K1 has 19 documented interactions with other supplements and medications. The most notable include Warfarin, Ampicillin, Cefixime, Cefpodoxime, and Cefuroxime.
What should you not take with Vitamin K1?
Vitamin K1 is flagged against 1 substance in the database, including Warfarin. Review these with a clinician before combining, especially alongside prescription medications.
What works well with Vitamin K1?
Vitamin K1 pairs synergistically with Evening Primrose Oil, Flaxseed Oil, MCT Oil, Vitamin K2, and Vitamin K2 MK-4 in the NutriStack database. Synergy still depends on dose and timing; open any pair for the detail.
Can you take Vitamin K1 with Warfarin?
NutriStack classifies the Vitamin K1 and Warfarin pairing as conflict: Vitamin K1 (phytonadione) directly reverses warfarin's anticoagulant effect. Even small, regular doses found in multivitamins (25 mcg/day) have been shown to lower the... Avoid vitamin K1 supplements unless your prescriber has specifically directed you to take them. If a multivitamin containing vitamin K1 is...
Check your whole stack
See how vitamin k1 fits your routine.
NutriStack screens your full stack for interactions and timing conflicts, and updates the moment you change it.