Trusted, medically reviewed health information • Not a substitute for medical advice
Medically Verified MonographPrescriptionClass: Vitamin K Antagonist Anticoagulant

Warfarin

Generic Name: Warfarin Sodium

Common Brand Names: Coumadin, Jantoven
Dosage Form:Oral Tablets, Powder for Injection
Route:Oral, Intravenous
Pregnancy Category:Category X
Last Reviewed:9/21/2026

Seek Urgent Medical Attention If:

You experience severe allergic reaction symptoms (swelling of the face, lips, tongue, or throat causing difficulty breathing), severe rash with skin peeling, sudden intense chest pain, or symptoms of overdose. Call emergency medical services immediately.

Uses & Medical Indications

Prophylaxis and treatment of venous thromboembolism, pulmonary embolism, and thromboembolic complications associated with atrial fibrillation or cardiac valve replacement.

Medical Conditions Treated:

Deep Vein Thrombosis (DVT), Pulmonary Embolism (PE), Atrial Fibrillation

Dosage & Administration Guidelines

Adult Dosage

Individualized; typically initiated at 2 mg to 5 mg daily, adjusted based on PT/INR results.

Pediatric Dosage

Strictly specialized pediatric dosing based on weight and target INR.

Elderly / Geriatric Considerations

Elderly patients often require lower maintenance doses due to increased sensitivity.

Maximum Dose Limit

Determined strictly by target INR range (usually 2.0-3.0).

Renal Impairment:

No specific dosage adjustment needed; monitor INR closely.

Hepatic Impairment:

Use with extreme caution; hepatic impairment impairs clotting factor synthesis.

Side Effects & Safety Warnings

Common Side Effects

Minor bruising, bleeding gums, prolonged bleeding from cuts.

Serious Adverse Reactions

Major hemorrhage, intracranial bleeding, warfarin-induced skin necrosis, purple toes syndrome.

Contraindications:

Pregnancy (teratogenic), active bleeding, hemorrhagic tendencies, threatened abortion.

Important Warnings & Precautions:

Black Box Warning: Can cause major or fatal bleeding. Regular INR monitoring required.

Interactions (Drugs, Food & Alcohol)

Drug-Drug Interactions:

Extensive: NSAIDs, antibiotics (metronidazole, fluoroquinolones), amiodarone, antifungals, SSRIs.

Food & Dietary Interactions:

Maintain consistent dietary vitamin K intake (green leafy vegetables).

Alcohol Interaction Warning:

Acute alcohol increases INR; chronic heavy drinking decreases efficacy.

Identified Clinical Drug Interactions for Warfarin:

Warfarin + AspirinMajor Interaction

Significantly increased risk of severe, life-threatening gastrointestinal hemorrhage and bleeding.

Check in Tool →
Warfarin + CiprofloxacinMajor Interaction

Marked enhancement of anticoagulant effect with sudden spikes in INR and severe hemorrhage.

Check in Tool →

Pregnancy & Breastfeeding Safety

Pregnancy Safety

Contraindicated in pregnancy due to high risk of fatal embryopathy and hemorrhage.

Breastfeeding / Lactation

Does not enter breast milk in significant amounts; generally considered compatible.

Patient Counseling & Practical Advice

How to Take:

Keep your diet consistent regarding green leafy salads. Avoid sports with injury risks.

What to Do if You Miss a Dose:

Take as soon as possible on the same day. Never double the dose the next day.

Recommended Monitoring & Lab Tests:

International Normalized Ratio (INR), hematocrit, signs of bleeding.

Trustworthy Sources & Medical Review

Content for Warfarin was synthesized and fact-checked against standardized regulatory monographs, official pharmacopoeias, and national health authorities:

  • Central Drugs Standard Control Organization (CDSCO) — National List of Essential Medicines
  • World Health Organization (WHO) — Model List of Essential Medicines 23rd List
  • Indian Pharmacopoeia Commission (IPC) — Indian Pharmacopoeia Drug Monographs
  • National Health Service (NHS) — Medicines A to Z Clinical Guidelines
Reviewer Credentials: PharmD, Clinical PharmacologistLast Reviewed Date: 9/21/2026

The information provided on this website is for educational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions you may have regarding a medical condition.