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This is an information resource — not medical advice.

PillCodex provides general educational information about medications. This content is not a substitute for professional medical advice, diagnosis, or treatment. Never start, stop, or change a medication based on what you read here. Always speak to your doctor, pharmacist, or qualified healthcare provider with questions about your medications.

🚨 If you are experiencing a medical emergency or think you may have taken too much of a medication, call emergency services (911 in the US) or go to your nearest emergency room immediately.

Anticoagulant (Blood Thinner)🔒 Prescription only

What Is Warfarin (Coumadin) Used For?

Brand names: Coumadin, Jantoven

Warfarin is a powerful blood thinner used to prevent and treat dangerous blood clots. It requires careful monitoring and has many food and drug interactions.

What is Warfarin used for?

Prevention of deep vein thrombosis and pulmonary embolism
Atrial fibrillation (prevents stroke)
Mechanical heart valve patients
Treatment of existing blood clots

How does Warfarin work?

Warfarin blocks vitamin K which the liver needs to make clotting factors. Without these factors, blood takes longer to clot, reducing dangerous clot risk.

Dosage information

💊Available forms

1mg through 10mg tablets (multiple strengths)

📏Typical dosage

Highly individualized based on INR blood tests. Typical dose is 2–10mg daily, adjusted frequently based on monitoring.

⚠️ Dosage varies by individual. Always follow your doctor's or pharmacist's instructions — never self-dose based on general information.

Side effects

Common

Bleeding more easily
Bruising easily
Prolonged bleeding from cuts

⚠️ Serious — contact your doctor

Serious internal bleeding (emergency for unusual pain, swelling, or headache)
Intracranial hemorrhage
Skin necrosis (rare)

Important warnings

Requires regular INR blood tests — dose will change frequently

MANY drug and food interactions — tell every doctor and pharmacist you take warfarin

Consistent vitamin K intake essential — do not suddenly change green vegetable consumption

Seek emergency care for any signs of unusual bleeding

Wear a medical alert bracelet

Drug interactions

These substances may interact with Warfarin. This is not a complete list — always tell your doctor and pharmacist ALL medications and supplements you take.

AspirinIbuprofenMany antibioticsAntifungalsAmiodaroneVitamin K supplementsSt John's WortFish oilGarlic

Pregnancy & breastfeeding

🤰 CONTRAINDICATED in pregnancy — can cause fetal harm and bleeding

Always consult your doctor or obstetrician before taking any medication during pregnancy or while breastfeeding.

Frequently asked questions

What is warfarin used for?

Warfarin prevents and treats dangerous blood clots, reduces stroke risk in atrial fibrillation, and is used in people with mechanical heart valves.

What foods should I avoid with warfarin?

You don't need to avoid vitamin K foods (green vegetables) but must eat them consistently. Sudden large changes in spinach, kale, broccoli will change your INR. Limit alcohol and cranberry juice.

What is INR and why is it important?

INR measures how long your blood takes to clot. Warfarin dosing aims for a target range (usually 2–3). Too low = clot risk; too high = serious bleeding risk. Regular testing is essential.

Can I take ibuprofen or aspirin with warfarin?

Avoid both — they significantly increase bleeding risk. Use paracetamol (acetaminophen) for pain relief instead.

What if I miss a dose of warfarin?

Take the missed dose the same day if you remember. If not until the next day, skip it — never double up. Record the missed dose and inform your anticoagulation clinic.

Related medications

💊AspirinNSAID / Antiplatelet Agent 💊LisinoprilACE Inhibitor 💊AtorvastatinStatin (HMG-CoA reductase inhibitor)

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This is an information resource — not medical advice.

🚨 If you are experiencing a medical emergency or think you may have taken too much of a medication, call emergency services (911 in the US) or go to your nearest emergency room immediately.

Information on this page is sourced from general pharmaceutical references and is provided for educational purposes only. Drug information may change — always verify with your pharmacist or prescriber. PillCodex.com is not affiliated with any pharmaceutical company.