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What is warfarin?

Warfarin is an anticoagulant (blood thinner). Warfarin reduces the formation of blood clots.

Warfarin is used to prevent heart attacks, strokes, and blood clots in veins and arteries.

Warfarin may also be used for purposes other than those listed in this medication guide.

Precautions

Instructions

Side-effects

Interactions

Precautions

Do not take this medicine if you have:

• a bleeding disorder such as hemophilia;
• a blood cell disorder such as anemia;
• a stomach ulcer or bleeding in the stomach;
• a history of aneurysm, blood clot, or bleeding in your brain; or
• an infection of your heart, fluid or swelling around your heart.

FDA pregnancy category X. This medication can cause miscarriage, stillbirth, birth defects, or fatal bleeding in an unborn baby. Do not use warfarin if you are pregnant. Tell your doctor right away if you become pregnant during treatment. Use an effective form of birth control while you are using this medication.

Before taking warfarin, tell your doctor if you have:

• kidney disease;
• liver disease;
• celiac sprue (an intestinal disorder);
• a recent injury, surgery, or medical emergency;
• high blood pressure;
• severe or uncontrolled diabetes;
• polycythemia vera;
• congestive heart failure;
• cancer;
• overactive thyroid;
• a seizure disorder for which you take an anticonvulsant such as phenytoin (Dilantin) or phenobarbital (Luminal); or
• a connective tissue disorder such as Marfan Syndrome, Sjogren syndrome, scleroderma, rheumatoid arthritis, or lupus.

If you have any of these conditions, you may not be able to use warfarin, or you may need a dosage adjustment or special tests during treatment.

Warfarin may pass into breast milk and cause bleeding problems in the nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

Older adults and people who are severely ill or debilitated may have a greater risk of bleeding while taking warfarin. Talk with your doctor about your individual risk.

Warfarin should not be given to anyone younger than 18 years old.

Tell your doctor (or dentist) that you are taking warfarin before you take an antibiotic or before having surgery.

You should not take acetaminophen (Tylenol), aspirin, or NSAIDs (non-steroidal anti-inflammatory drugs) unless your doctor has told you to. NSAIDs include celecoxib (Celebrex), diclofenac (Voltaren), ibuprofen (Motrin, Advil), indomethacin, naproxen (Aleve, Naprosyn), piroxicam (Feldene), and others.These medicines may affect blood clotting and could cause serious bleeding in your stomach or intestines.

Avoid sudden changes in your diet. Vitamin K decreases the effects of warfarin. Large amounts of vitamin K are found in foods such as liver, broccoli, brussels sprouts, spinach, Swiss chard, coriander, collards, cabbage, and other green leafy vegetables. Do not change the amount of these foods in your diet without first talking to your doctor.

Avoid eating cranberries, drinking cranberry juice, or taking cranberry herbal products.

Avoid drinking alcohol, which can increase some of the side effects of this medication.

Avoid sports or activities that could result in a bruising or bleeding injury. Use extra caution to avoid cuts when brushing your teeth or shaving.

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Instructions

Seek emergency medical attention if you think you have used too much of this medicine.

Overdose symptoms may include bruising, broken blood vessels under the skin, excessive bleeding from cuts or wounds, blood in the urine or stools, and heavy menstrual periods in women.

Take the missed dose as soon as you remember, and call your doctor as soon as possible. You may take two doses on the same day, but do not take two doses at the same time.

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Side-effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have any of these serious side effects:

• skin changes or discoloration anywhere on your body;
• purple toes or fingers;
• pain in your stomach, back, or sides;
• low fever, loss of appetite, dark urine, jaundice (yellowing of the skin or eyes);
• diarrhea, fever, chills, body aches, flu symptoms;
• easy bruising or bleeding that will not stop;
• blood in your urine;
• black, bloody, or tarry stools;
• nosebleeds, bleeding gums, coughing up blood;
• feeling weak or light-headed;
• sudden headache, confusion, problems with vision, speech, or balance;
• sudden leg or foot pain; or
• sudden numbness or weakness, especially on one side of the body.

Less serious side effects may include:

• nausea, vomiting, stomach pain;
• gas and bloating; or
• hair loss.

This is not a complete list of side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.

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Interactions

Warfarin interacts with many other drugs, and these interactions can be dangerous, even fatal. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor. Keep a list with you of all the medicines you use and show this list to any doctor or other healthcare provider who treats you.

Warfarin can interact with the following herbal (botanical) products:

• bromelains;
• coenzyme Q10;
• danshen;
• dong quai;
• garlic;
• ginkgo biloba;
• ginseng; or
• St. John's wort.

Do not use any of these products without first asking your doctor. Some of these herbal products can cause you to bleed while you are also taking warfarin.

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