Find & Manage Your Patient Assistance Programs
Estimated patient savings $600,000,000.00
Warfarin sodium oral

Important Note

The following information is intended to supplement, not substitute for, the expertise and judgment of your physician, pharmacist or other healthcare professional. It should not be construed to indicate that use of the drug is safe, appropriate, or effective for you. Consult your healthcare professional before using this drug.





This medication is a blood thinner used to keep blood flowing smoothly and prevent the formation of blood clots.

How To Use

Take this exactly as prescribed. Try to take this medication at the same time each day so you remember to take it. Your dose may be adjusted several times based on lab tests. Do not stop taking this without your doctor's approval.

Side Effects

Loss of appetite, nausea, diarrhea or blurred vision may occur at first as your body adjusts to the medication. Inform your doctor if you experience: unusual bleeding or bruising, blood in the urine, black stools, severe headache. In the unlikely event you have an allergic reaction to this drug, seek medical attention immediately. Symptoms of an allergic reaction include: rash, itching, swelling, dizziness, trouble breathing. If you notice other effects not listed above, contact your doctor or pharmacist.


Before using this drug tell your doctor your medical history especially of: ulcers, unusual menstrual periods, diabetes, liver or kidney disease, high blood pressure, arthritis, thyroid problems, all recent infections, recent surgery, drug and food allergies. The FDA has stated that generic warfarin products are interchangeable. However, consult your doctor and pharmacist before switching warfarin products. Do not stop taking any medications that you are currently taking unless directed to do so by your doctor. If you have an illness that causes vomiting, diarrhea, or fever for more than a few days, contact your doctor as these problems can change the effect of this drug. Limit your consumption of alcoholic beverages. Ask your doctor how much, if any, alcohol you may consume. When receiving warfarin, avoid sudden changes in dietary habits. Avoid ingesting unusual increases or decreases of foods high in Vitamin K (liver, broccoli, cauliflower, cabbage, kale, spinach and other green leafy vegetables, green tea, certain vegetables, and certain vitamin supplements). It is best to avoid strictly vegetarian diets that consist of foods high in vitamin K. While taking this medication, be extra careful to avoid injuries. This medication can cause heavy bleeding. Use an electric razor and be careful brushing your teeth. Caution is advised when using this drug in the elderly because they may be more sensitive to the effects of the drug. Warfarin should not be used during pregnancy. If you become pregnant or think you may be pregnant, inform your doctor immediately. This drug is excreted into breast milk. While to date, no problems have been noted in nursing infants, consult your doctor before you breast-feed.

Drug Interactions

Many drugs interact with this medication. Before using this drug tell your doctor of all prescription and nonprescription drugs you may use especially any of the following: aspirin or aspirin-like drugs, anabolic steroids, barbiturates, clofibrate, phenylbutazone, disulfiram, cimetidine, sulfa-drugs, metronidazole, vitamin E, cholestyramine, phenytoin, erythromycin-like antibiotics, propylthiouracil, injectable antibiotics, griseofulvin, ethchlorvynol, quinidine, quinine, thyroid drugs, allopurinol, glucagon, rifamycins, glutethimide, aminoglutethimide, chloramphenicol, carbamazepine, vitamin K (or its derivatives), dextrothyroxine, anti-inflammatory medication used for arthritis or fever reduction, penicillin-type drugs, amiodarone, omeprazole, sulfinpyrazone, chloral hydrate, "statin" drugs (e.g., lovastatin), propranolol, tamoxifen, quinolone antibiotics (e.g., ciprofloxacin), SSRI antidepressants (e.g., fluoxetine), gemfibrozil, azole antifungals (e.g., fluconazole, miconazole, including vaginal dose forms), birth control pills, dong quai, ginkgo biloba, ginseng. It is important that all doctors and dentists treating you know you take warfarin. Do not start or stop any medicine without doctor or pharmacist approval.


If overdose is suspected, contact your local poison control center or emergency room immediately. Symptoms of overdose may include bleeding, fast heartbeat, nausea, vomiting, stomach pain, diarrhea, and discoloration of urine or stools.


Do not share this medication with others.

Missed Dose

If you miss a dose, take as soon as remembered; do not take if it is almost time for the next dose, instead, skip the missed dose and resume your usual dosing schedule. Do not "double-up" the dose to catch up. Keep a record of missed doses to give to your doctor. Call your doctor if you miss 2 or more doses.


Store at room temperature between 59 and 86 degrees F (between 15 and 30 degrees C) away from moisture and sunlight. Do not store in the bathroom.

Medical Alert

Your condition can cause complications in a medical emergency. For enrollment information call MedicAlert at 1-800-854-1166 (USA), or 1-800-668-1507 (Canada).