Warfarin

Generic Name: warfarin (WAR far in)
Brand Name: Coumadin, Jantoven

What is warfarin?

Warfarin is an anticoagulant (blood thinner). It 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 not listed in this medication guide.

Important information about warfarin

Follow your doctor's instructions about taking warfarin while you are pregnant. Warfarin can harm an unborn baby or cause birth defects. However, the benefits of preventing blood clots in certain women may outweigh any risks to the baby.

Never take a double dose of this medication.

You should not take warfarin if you have a bleeding or blood cell disorder, blood in your urine or stools, an infection of the lining of your heart, stomach bleeding, bleeding in the brain, recent or upcoming surgery, or if you need a spinal tap or spinal anesthesia (epidural).

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Warfarin may cause you to bleed more easily, especially if you have: a history of bleeding problems, high blood pressure or severe heart disease, kidney or liver disease, cancer, surgery or a medical emergency, a disease affecting the blood vessels in your brain, a history of stomach or intestinal bleeding, if you are 65 or older, or if you are severely ill or debilitated.

Many drugs (including some over-the-counter medicines and herbal products) can cause serious medical problems or death if you take them with warfarin. It is very important to tell your doctor about all medicines you have recently used.

Ask your doctor before taking any medicine for pain, arthritis, fever, or swelling. These medicines may affect blood clotting and may also increase your risk of stomach bleeding.

Any doctor, dentist, surgeon, or other medical care provider who treats you should know that you are taking warfarin.

Avoid making any changes in your diet without first talking to your doctor.

Before taking warfarin

You should not take warfarin if you are allergic to it, or if you have:

• hemophilia or any bleeding disorder that is inherited or caused by disease;

• a blood cell disorder such as anemia (lack of red blood cells) or a low level of platelets in your blood;

• blood in your urine or stools, or if you have been coughing up blood;

• an infection of the lining of your heart (also called bacterial endocarditis);

• stomach or intestinal bleeding or ulcer;

• recent head injury, aneurysm, or bleeding in the brain;

• if you have recently had or will soon have any type of surgery (especially brain, spine, or eye surgery); or

• if you undergo a spinal tap or receive spinal anesthesia (epidural).

You should not take warfarin if you cannot be reliable in taking it because of alcoholism, psychiatric problems, dementia, or similar conditions.

Warfarin may cause you to bleed more easily, especially if you have:

• a history of bleeding problems;

• high blood pressure or severe heart disease;

• kidney or liver disease;

• cancer;

• surgery or a medical emergency;

• a disease affecting the blood vessels in your brain;

• a history of stomach or intestinal bleeding;

• if you are 65 or older; or

• if you are severely ill or debilitated.

To make sure you can safely take warfarin, tell your doctor if you have any of these other conditions:

• celiac sprue (an intestinal disorder);

• diabetes;

• congestive heart failure;

• overactive thyroid;

• a connective tissue disorder such as Marfan Syndrome, Sjogren syndrome, scleroderma, rheumatoid arthritis, or lupus; or

• if you have ever had low blood platelets after receiving heparin.

Follow your doctor's instructions about taking warfarin while you are pregnant. Warfarin can harm an unborn baby or cause birth defects. However, the benefits of preventing blood clots in certain women may outweigh any risks to the baby. Tell your doctor right away if you become pregnant during treatment. Use effective birth control while you are using warfarin.

It is not known whether warfarin passes into breast milk or if it could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

How should I take warfarin?

Take warfarin exactly as prescribed by your doctor. Follow the directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended. Never take a double dose of this medication.

Your doctor may occasionally change your dose to make sure you get the best results.

Take warfarin at the same time every day. Warfarin can be taken with or without food.

Avoid dieting to lose weight while taking warfarin. Tell your doctor if your body weight changes for any reason.

Call your doctor if you have any illness with diarrhea, fever, chills, body aches, or flu symptoms.

While taking warfarin, your blood will need to be tested often. Visit your doctor regularly.

Wear a medical alert tag or carry an ID card stating that you take warfarin. Any doctor, dentist, surgeon, or other medical care provider who treats you should know that you are taking this medication. You may need to stop taking the medicine for a short time if you need antibiotics, surgery, dental work, a spinal tap, or spinal anesthesia (epidural).

Store at room temperature away from heat, moisture, and light.

See also: Warfarin dosage (in more detail)

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose can cause excessive bleeding.

What should I avoid while taking warfarin?

Ask your doctor before taking any medicine for pain, arthritis, fever, or swelling. This includes acetaminophen (Tylenol), aspirin, celecoxib (Celebrex), ibuprofen (Advil, Motrin), diclofenac (Cataflam, Voltaren), indomethacin (Indocin), naproxen (Aleve, Naprosyn), piroxicam (Feldene), and others. These medicines may affect blood clotting and may also increase your risk of stomach bleeding.

Do not eat large amounts of foods high in vitamin K (such as liver, leafy green vegetables or vegetable oils). Vitamin K can make warfarin less effective. Avoid making any changes in your diet without first talking to your doctor.

Grapefruit and grapefruit juice may interact with warfarin and lead to unwanted side effects. Discuss the use of grapefruit products with your doctor.

Warfarin side effects

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

Stop using warfarin and call your doctor at once if you have a serious side effect such as:

• pain, swelling, hot or cold feeling, skin changes, or discoloration anywhere on your body;

• sudden and severe leg or foot pain, foot ulcer, purple toes or fingers;

• sudden headache, dizziness, or weakness;

• unusual bleeding (nose, mouth, vagina, or rectum), bleeding from wounds or needle injections, any bleeding that will not stop;

• easy bruising, purple or red pinpoint spots under your skin;

• blood in your urine, black or bloody stools, coughing up blood or vomit that looks like coffee grounds;

• pale skin, feeling light-headed or short of breath, rapid heart rate, trouble concentrating;

• dark urine, jaundice (yellowing of the skin or eyes);

• pain in your stomach, back, or sides;

• urinating less than usual or not at all;

• numbness or muscle weakness; or

• any illness with diarrhea, fever, chills, body aches, or flu symptoms.

Less serious warfarin side effects may include:

• nausea, vomiting, mild stomach pain;

• bloating, gas; or

• altered sense of taste.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Warfarin side effects (in more detail)

What other drugs will affect warfarin?

Many drugs (including some over-the-counter medicines and herbal products) can cause serious medical problems or death if you take them with warfarin. Not all possible drug interactions are listed in this medication guide. It is very important to tell your doctor about all medicines you have recently used, especially:

• any other medications to prevent blood clots;

• an antibiotic, antifungal medication, sulfa drug, or medicine to treat tuberculosis;

• an antidepressant such as citalopram (Celexa), fluoxetine (Prozac, Rapiflux, Sarafem, Selfemra, Symbyax), paroxetine (Paxil, Pexeva), sertraline (Zoloft), and others;

• antifungal medications such as fluconazole (Diflucan), miconazole (Monistat, Oravig), voriconazole (Vfend), and others;

• herbal (botanical) products including coenzyme Q10, cranberry, echinacea, garlic, ginkgo biloba, ginseng, goldenseal, or St. John's wort;

• secobarbital (Seconal) and others barbiturates; or

• seizure medication such as carbamazepine (Carbatrol, Equetro, Tegretol), phenobarbital (Solfoton), phenytoin (Dilantin).

This list is not complete and many other drugs can interact with warfarin. This includes prescription, over-the-counter, vitamin, and herbal products. Give a list of all your medicines to any healthcare provider who treats you.

Where can I get more information?

• Your pharmacist can provide more information about warfarin.