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Warfarin Dosage Calculator

Professional blood thinner dosage calculator with INR tracking, dose adjustment recommendations, drug interaction warnings, and trend analysis.

Patient Information

Enter patient details

INR & Current Dose

Latest values

INR Gauge & Status

Visual INR monitoring
0.0 0 INR 8+
No Data
Low
Therapeutic
High
Danger
INR < 2.0
Increase Dose
INR 2.0 - 3.0
Maintain
INR 3.0 - 4.0
Reduce Dose
INR > 4.0
Hold Dose

INR History Tracker

Add readings over time
No INR readings recorded yet. Add your first reading above.

INR Trend Chart

Track your INR over time

Drug Interaction Warnings

Common interacting medications

These medications can significantly affect warfarin levels. Always consult your physician.

Aspirin / NSAIDs
Increases bleeding risk significantly
HIGH
Amiodarone
Increases INR by 50-100%
HIGH
Fluconazole / Voriconazole
Strong CYP2C9 inhibitor, raises INR
HIGH
Amoxicillin / Azithromycin
Moderate INR increase possible
MODERATE
Omeprazole / Pantoprazole
May increase INR slightly
MODERATE
St. John's Wort
Decreases warfarin effectiveness
MODERATE
Cranberry Juice
May increase INR moderately
LOW
Green Leafy Vegetables
High Vitamin K may decrease INR
LOW
Heparin / LMWH
Additive anticoagulant effect
HIGH
Clopidogrel / Ticagrelor
Dual therapy increases bleeding
MODERATE

How It Works

Understanding warfarin dosing
1

Enter Patient Data

Input patient weight, age, indication for warfarin therapy, and select the appropriate target INR range.

2

Record INR Value

Enter the current INR lab result and the warfarin dose the patient is currently taking.

3

Calculate Dosage

Our algorithm applies evidence-based dose adjustment rules and generates personalized recommendations.

4

Track & Monitor

Record INR history, visualize trends, and get next test date recommendations for ongoing management.

Medical Disclaimer: This calculator is for educational and informational purposes only. It is NOT a substitute for professional medical advice, diagnosis, or treatment. Always consult your physician or healthcare provider before making any changes to your warfarin dosage. Never disregard professional medical advice or delay seeking it because of this tool. Individual dose adjustments require clinical judgment considering the patient's complete medical history, concurrent medications, diet, and lab results.