What kind of interaction is it?

Caution: an interaction that may reduce efficacy or raise side-effect risk and warrants monitoring.

Is this interaction backed by published research?

Yes. NutriStack lists 2 citation rows for the Dicloxacillin + Vitamin K2 pair, each linking to PubMed by PMID where available. Full sourcing methodology at https://nutristackapp.com/methodology/interactions.

Supplement × Prescription·a caution·Emerging evidence

Dicloxacillin + Vitamin K2

Q: Can I take Dicloxacillin and Vitamin K2 together?

Possibly, but with caution. Dicloxacillin and Vitamin K2 have a documented caution-tier interaction. Broad-spectrum and beta-lactam antibiotics can disrupt gut flora that synthesize vitamin K, theoretically reducing endogenous vitamin K availability. For most people on a short dicloxacillin course this is clinically negligible, but the effect is most relevant in patients on warfarin, where antibiotic-associated reductions in vitamin K can enhance anticoagulant effect.

Q: How does this affect a NutriStack Stack Score?

-5 to your Stack Score per scored caution row.

Caution Emerging evidence

Broad-spectrum and beta-lactam antibiotics can disrupt gut flora that synthesize vitamin K, theoretically reducing endogenous vitamin K availability. For most people on a short dicloxacillin course this is clinically negligible, but the effect is most relevant in patients on warfarin, where antibiotic-associated reductions in vitamin K can enhance anticoagulant effect.

Supplement × Prescription

Open the interaction checker → Read the methodology

From the database

What the row says.

Every entry follows the same shape: what is happening, the mechanism, and the recommendation.

Substances

Dicloxacillin and Vitamin K2

Pair type

Caution

Evidence

Emerging

Source citations

Scope

Supplement × Prescription

Last verified

June 4, 2026

CautionEmerging evidence

What is happening. Broad-spectrum and beta-lactam antibiotics can disrupt gut flora that synthesize vitamin K, theoretically reducing endogenous vitamin K availability. For most people on a short dicloxacillin course this is clinically negligible, but the effect is most relevant in patients on warfarin, where antibiotic-associated reductions in vitamin K can enhance anticoagulant effect.

Mechanism. Suppression of vitamin K-producing intestinal bacteria by the antibiotic can lower menaquinone (vitamin K2) supply; supplemental vitamin K offsets this but the interaction matters chiefly for vitamin-K-antagonist anticoagulation.

Recommendation. No routine action is needed for healthy individuals taking a vitamin K supplement. Patients on warfarin should have INR monitored during and after antibiotic therapy, as flora-related changes in vitamin K status can alter anticoagulation.

Stack Score

How it moves the number.

Effect on the composite score

If both Dicloxacillin and Vitamin K2 are in the same stack, this pair applies −5 to your Stack Score (per scored caution row).

The full algorithm, the clamping rules, and four worked stacks are at /methodology/stack-score.

Sources

Sources, by evidence tier.

Every claim on this page is cited. PMIDs link straight to PubMed.

Reference material

1Conly JM, Stein K. The production of menaquinones (vitamin K2) by intestinal bacteria and their role in maintaining coagulation homeostasis. Prog Food Nutr Sci. 1992.Needs sourceNo link
2Baillargeon J, et al. Concurrent use of warfarin and antibiotics and the risk of bleeding in older adults. Am J Med. 2012.Needs sourceNo link

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