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Vitamin C × Warfarin

MINOR INTERACTION — Possible Evidence

⚠️ Mechanism

High-dose vitamin C may affect warfarin clearance, though evidence is weak.

📋 Effect

Possible minor INR changes at very high doses (>5g/day)

💊 Management

Monitor INR if taking high-dose vitamin C. Normal dietary intake is safe.

Plain Language Summary

This combination is generally safe at normal dietary levels, but very high doses of vitamin C may slightly affect how warfarin works. Taking more than 5 grams of vitamin C per day could potentially cause minor changes in your blood clotting levels.

Source

Harris JE. JAMA 1971 (case report only)

Supporting Research

Vitamin E supplementation in pregnancy PMID:26343254 DOI:10.1002/14651858.CD004069.pub3 2015
Nutritional interventions for preventing and treating pressure ulcers PMID:38345088 DOI:10.1002/14651858.CD003216.pub3 2024
Does Vitamin C Supplementation Provide a Protective Effect in Periodontal Health? A Systematic Review and Meta-Analysis PMID:39201285 DOI:10.3390/ijms25168598 2024
Circulating vitamin C concentration and risk of cancers: a Mendelian randomization study PMID:34325683 DOI:10.1186/s12916-021-02041-1 2021
Vitamin C in Critically Ill Patients: An Updated Systematic Review and Meta-Analysis PMID:34684565 DOI:10.3390/nu13103564 2021
Reminder packaging for improving adherence to self-administered long-term medications PMID:21901694 DOI:10.1002/14651858.CD005025.pub3 2011
Nutritional interventions for preventing and treating pressure ulcers PMID:24919719 DOI:10.1002/14651858.CD003216.pub2 2014
Interventions to reduce haemorrhage during myomectomy for fibroids PMID:25125317 DOI:10.1002/14651858.CD005355.pub5 2014
Medical Disclaimer: This interaction record is for informational and educational purposes only and does not constitute medical advice. Drug-supplement interactions can be dangerous. Always consult your healthcare provider or pharmacist before combining any supplement with prescription medications. Do not stop or change any medication without professional guidance.