MedlinePlus Drug Information: Warfarin

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Other drug names:	A-Am An-Az B C-Ch Ci-Cz D-Dh Di-Dz E F G H I-J K-L M-Mh Mi-Mz N-Nh Ni-Nz O P-Pl Pm-Pz Q-R S-Sn So-Sz T-To Tp-Tz U-V W-Z 0-9

Warfarin

(war' far in)

Brand name(s): Coumadin

Contents of this page:
Why is this medication prescribed? How should this medicine be used? Other uses for this medicine What special precautions should I follow? What special dietary instructions should I follow?	What should I do if I forget a dose? What side effects can this medication cause? What storage conditions are needed for this medicine? In case of emergency/overdose What other information should I know?

Why is this medication prescribed?

Warfarin is used to prevent blood clots from forming or growing larger. It is often prescribed for patients with certain types of irregular heartbeat and after a heart attack or heart valve replacement surgery. It works by stopping the formation of substances that cause clots.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

How should this medicine be used?

Warfarin comes as a tablet to take by mouth. It usually is taken once a day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take warfarin exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Continue to take warfarin even if you feel well. Do not stop taking warfarin without talking to your doctor.

Other uses for this medicine

Warfarin also is used with other drugs in the treatment of some lung cancers. Talk to your doctor about the possible risks of using this drug for your condition.

What special precautions should I follow?

Before taking warfarin,

tell your doctor and pharmacist if you are allergic to warfarin, aspirin, tartrazine (a yellow dye in some medications and processed foods), or any other drugs.
tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially other heart medications; antibiotics; aspirin and other non-steroidal antiiflammatory drugs such as ibuprofen (Advil, Motrin) and naproxen (Aleve, Naprosyn); cimetidine (Tagamet); medications for cancer, depression, diabetes, digestive problems, epilepsy, gout, high cholesterol, and thyroid problems; and vitamins. Many medications interfere with the effectiveness of warfarin. It is important that you tell your doctor every medication that you take, including nonprescription medications. Do not take any new medications without talking to your doctor.
tell your doctor and pharmacist what herbal products you are taking, especially bromelains, coenzyme Q10, danshen, dong quai, garlic, Ginkgo biloba, and St. John's wort. Do not start taking any herbal products without talking to your doctor.
tell your doctor if you have had your prostate removed, have or have ever had a stroke, kidney or liver disease, high blood pressure, a thyroid condition, diabetes, tuberculosis, a bleeding disorder, ulcers, leukemia, vitamin C deficiency, colostomy bag, or intestinal disease.
tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking warfarin, call your doctor.
if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking warfarin. Your doctor may tell you to stop taking warfarin 3 days before your procedure. Follow these directions.
ask your doctor about the safe use of alcohol while you are taking warfarin.

What special dietary instructions should I follow?

Do not increase your consumption of foods containing vitamin K, such as liver, green leafy vegetables, broccoli, and cauliflower, without discussing your diet with your doctor.

What should I do if I forget a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one. Record the date of the missed dose and tell your doctor at your next visit, since missing a dose of warfarin may alter your blood clotting tests. If you miss doses for 2 or more days, call your doctor immediately.

What side effects can this medication cause?

Although side effects from warfarin are not common, they can occur. Warfarin may turn your urine red-orange; this effect is harmless. If you think your urine contains blood, call your doctor immediately. Tell your doctor if any of these symptoms are severe or do not go away:

headache
upset stomach
diarrhea
fever
skin rash

If you experience any of the following symptoms, call your doctor immediately:

unusual bleeding or bruising
black or bloody stools
blood in the urine
tiredness
unexplained fever
chills
sore throat
stomach pain

What storage conditions are needed for this medicine?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

In case of emergency/overdose

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

What other information should I know?

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your response to warfarin.

Warfarin prevents blood from clotting so it may take longer than usual for you to stop bleeding if you are cut or injured. Avoid activities that have a high risk of causing injury. Call your doctor if bleeding is unusual.

Carry an identification card or wear a bracelet that indicates that you take warfarin. Ask your pharmacist or doctor how to obtain this card or bracelet. List your name, medical problems, drugs and dosages, and doctor's name and telephone number on the card. Tell any doctor or dentist that you visit that you are taking warfarin.

If you have an illness that causes vomiting, diarrhea, or fever for more than a few days, call your doctor. These problems can change the effectiveness of warfarin.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

Last Revised - 01/01/2003

American Society of Health-System Pharmacists, Inc. Disclaimer