Warfarin Drug Interactions

Anticoagulants, especially warfarin, have extensive drug and food interactions that affect bleeding risk.

Key Drug Interactions

→NSAIDs and aspirin: significantly increased bleeding risk
→Antibiotics: many alter gut flora affecting vitamin K — change INR
→Antifungals (azoles), amiodarone: increase warfarin effect
→Enzyme inducers (rifampicin, carbamazepine): reduce warfarin effect
→Other anticoagulants / antiplatelets: additive bleeding risk
→For DOACs: strong P-gp or CYP3A4 inhibitors/inducers significantly alter drug levels

Alcohol Interactions

→Alcohol increases bleeding risk and can interfere with INR monitoring for warfarin. Limit alcohol intake and avoid binge drinking.

Supplement and Food Interactions

→Vitamin K-rich foods (green leafy vegetables) affect warfarin — maintain a consistent diet rather than eliminating them. Fish oil, garlic, and ginkgo biloba may increase bleeding risk. St John's Wort reduces warfarin effectiveness.

Safety Note

Always tell your doctor and pharmacist about all prescription medicines, non-prescription medicines, vitamins, and herbal or dietary supplements before starting Warfarin. Keep an up-to-date medicines list to share with all healthcare providers.

Frequently Asked Questions

Can I take Warfarin with common over-the-counter medicines?

Some OTC medications interact with Warfarin. NSAIDs, aspirin, antihistamines, antacids, and herbal products can all have interactions. Ask your pharmacist to check for interactions before taking any new OTC product.

Can I drink alcohol while taking Warfarin?

Alcohol increases bleeding risk and can interfere with INR monitoring for warfarin. Limit alcohol intake and avoid binge drinking.

More About Warfarin

Dosage & Administration

Side Effects

Warnings & Precautions

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Medical Disclaimer: This drug reference is provided for informational purposes only and is not a substitute for professional medical advice. Always consult your physician or pharmacist before changing your medication. Information reviewed by the vHospital Editorial Team · Sources: WHO, BNF, FDA prescribing information.