What is the recommended dose of Vitamin K?

- **AI (adult males):** 120 μg/day; **Females:** 90 μg/day - **For bone health (K1):** 100-5,000 μg/day - **For bone health (K2 as MK-4):** 15-45mg/day (used in Japanese osteoporosis treatment) - *...

Is Vitamin K safe to take daily?

Vitamin K is rated "Prescription Interactions" based on clinical evidence. - **Oral:** Nausea, abdominal pain, diarrhea (uncommon) - **IV/IM (medical settings):** Anaphylactoid reactions, skin flushing, BP changes, dyspnea

Does Vitamin K interact with any medications?

Vitamin K has 1 known drug interaction, including interactions with Warfarin and vitamin K antagonists. Check with your doctor before combining with prescription medications.

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Ingredient Research

Graded against 173,636 supplements + 177 published clinical interactions, sourced from PubMed, FDA CAERS, openFDA, NIH DSLD

Vitamin K

MODERATE EVIDENCEVitaminLast updated April 5, 2026

AVELOR SUMMARY

Vitamin K is a fat-soluble vitamin essential for blood clotting, bone metabolism, and vascular health. K1 (phylloquinone) comes from leafy greens; K2 (menaquinone) comes from fermented foods and meat. Our research, from 24 RCTs, 13 meta-analyses, and 30,302 participants, shows it improves bone mineral density markers. The critical safety fact: vitamin K directly counteracts warfarin. If you're on blood thinners, vitamin K supplementation without medical supervision is dangerous.

EVIDENCE GRADES

Bone Mineral DensityModerate

Vascular Calcification markersModerate

Fracture Risk

Limited/Mixed evidence

OPTIMAL DOSAGE

AI (adult males): 120 μg/day; Females: 90 μg/day
For bone health (K1): 100-5,000 μg/day
For bone health (K2 as MK-4): 15-45mg/day (used in Japanese osteoporosis treatment)
For bone health (K2 as MK-7): 100-375 μg/day
No established UL (insufficient data, not proof of safety at any dose)
Best form: MK-7 (menaquinone-7) — longer half-life, more bioavailable than K1

Scan a supplement containing Vitamin K

DRUG INTERACTIONS

Warfarin and vitamin K antagonistsSevere

Counteracts drug effect

DO NOT supplement without doctor supervision if on warfarin.

SAFETY PROFILE

Side Effects

Oral: Nausea, abdominal pain, diarrhea (uncommon)
IV/IM (medical settings): Anaphylactoid reactions, skin flushing, BP changes, dyspnea

Drug Interactions

Nutrient Depletions

Orlistat — may reduce K absorption (fat-soluble). Take K 2+ hours before/after orlistat.
Bile acid sequestrants — may reduce K absorption. Take 4+ hours apart. Monitor long-term.
Broad-spectrum antibiotics — prolonged use may deplete K by killing gut bacteria that synthesize it.
Rifampicin — may reduce K-dependent coagulation factors.

Precautions

Pregnancy/Breastfeeding: Safe at recommended intake.
Warfarin users: Critical interaction. Must coordinate with prescriber.

WADA Status

Not Prohibited.

WHO SHOULD BE CAREFUL

HOW AVELOR SCORES THIS

Present at 90-200 μg (K1 or MK-7):✅ Green flag — supports bone and cardiovascular health

Combined with vitamin D:✅✅ Excellent pairing — synergistic for bone health

Patient on warfarin:🔴 Red flag — life-threatening interaction

No form specified:⚠️ Yellow flag — K1 vs K2 (MK-4 vs MK-7) have different kinetics

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Scan Your Vitamin K Supplement Browse all ingredients

Independently graded against 173,636 indexed supplements with 177 published clinical interactions, sourced from PubMed, FDA CAERS, openFDA, and NIH DSLD | Last updated: April 5, 2026

Not medical advice. Based on published clinical research and systematic reviews.

Vitamin K · interaction landscape

1 flagged

Dangerous

Moderate

Timing

Pre-op

Safety

Vitamin K: Drug Interactions

Vitamin K is the direct pharmacological antagonist of warfarin. Supplementing without cardiology supervision can cause dangerous clots.

Mechanism: Vitamin K is the direct antidote to warfarin. It activates the clotting factors warfarin inhibits, so it literally reverses warfarin's mechanism of action. Even dietary changes (more leafy greens) can destabilize INR.

Discuss with prescriber

Clinically significant interactions per published research. Talk to your prescriber or pharmacist before using this supplement if you take any of these.

Warfarin (Coumadin)
Vitamin K reactivates clotting factors II, VII, IX, and X, directly opposing warfarin.
RiskBlood clots, stroke, pulmonary embolism, or DVT from reduced anticoagulation.
ActionKeep vitamin K intake consistent (do not suddenly increase or decrease). Do not supplement vitamin K without cardiologist approval.
SourceFDA label, clinical standard

Educational information only. This is not medical advice. These statements have not been evaluated by the FDA. Talk to your prescriber before starting, stopping, or combining any supplement with prescription medication.

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Ingredient Research

Graded against 173,636 supplements + 177 published clinical interactions, sourced from PubMed, FDA CAERS, openFDA, NIH DSLD

Vitamin K

MODERATE EVIDENCEVitaminLast updated April 5, 2026

AVELOR SUMMARY

EVIDENCE GRADES

Bone Mineral DensityModerate

Vascular Calcification markersModerate

Fracture Risk

Limited/Mixed evidence

OPTIMAL DOSAGE

AI (adult males): 120 μg/day; Females: 90 μg/day
For bone health (K1): 100-5,000 μg/day
For bone health (K2 as MK-4): 15-45mg/day (used in Japanese osteoporosis treatment)
For bone health (K2 as MK-7): 100-375 μg/day
No established UL (insufficient data, not proof of safety at any dose)
Best form: MK-7 (menaquinone-7) — longer half-life, more bioavailable than K1

Scan a supplement containing Vitamin K

DRUG INTERACTIONS

Warfarin and vitamin K antagonistsSevere

Counteracts drug effect

DO NOT supplement without doctor supervision if on warfarin.

SAFETY PROFILE

Side Effects

Oral: Nausea, abdominal pain, diarrhea (uncommon)
IV/IM (medical settings): Anaphylactoid reactions, skin flushing, BP changes, dyspnea

Drug Interactions

Nutrient Depletions

Orlistat — may reduce K absorption (fat-soluble). Take K 2+ hours before/after orlistat.
Bile acid sequestrants — may reduce K absorption. Take 4+ hours apart. Monitor long-term.
Broad-spectrum antibiotics — prolonged use may deplete K by killing gut bacteria that synthesize it.
Rifampicin — may reduce K-dependent coagulation factors.

Precautions

Pregnancy/Breastfeeding: Safe at recommended intake.
Warfarin users: Critical interaction. Must coordinate with prescriber.

WADA Status

Not Prohibited.

WHO SHOULD BE CAREFUL

HOW AVELOR SCORES THIS

Present at 90-200 μg (K1 or MK-7):✅ Green flag — supports bone and cardiovascular health

Combined with vitamin D:✅✅ Excellent pairing — synergistic for bone health

Patient on warfarin:🔴 Red flag — life-threatening interaction

No form specified:⚠️ Yellow flag — K1 vs K2 (MK-4 vs MK-7) have different kinetics

RELATED RESEARCH

Acerola Cherry

Amla

BiotinBiotin is a cofactor for five carboxylase enzymes critical to metabolism: pyruva

Amla

Scan Your Vitamin K Supplement Browse all ingredients

Independently graded against 173,636 indexed supplements with 177 published clinical interactions, sourced from PubMed, FDA CAERS, openFDA, and NIH DSLD | Last updated: April 5, 2026

Not medical advice. Based on published clinical research and systematic reviews.

Vitamin K · interaction landscape

1 flagged

Dangerous

Moderate

Timing

Pre-op

Safety

Vitamin K: Drug Interactions

Vitamin K is the direct pharmacological antagonist of warfarin. Supplementing without cardiology supervision can cause dangerous clots.

Discuss with prescriber

Clinically significant interactions per published research. Talk to your prescriber or pharmacist before using this supplement if you take any of these.

Warfarin (Coumadin)
Vitamin K reactivates clotting factors II, VII, IX, and X, directly opposing warfarin.
RiskBlood clots, stroke, pulmonary embolism, or DVT from reduced anticoagulation.
ActionKeep vitamin K intake consistent (do not suddenly increase or decrease). Do not supplement vitamin K without cardiologist approval.
SourceFDA label, clinical standard

Discover More

Explore

Browse All 834 Ingredients Browse All 20 Conditions