Learning About Your Health

Coumadin (Warfarin)

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What is Coumadin (Warfarin)?

Coumadin is a "blood thinner" medication that prevents blood clotting. This medication is ordered for patients at risk for excessive blood clotting, such as those with artificial heart valves, irregular heart rhythms, or blood clots. Note: Coumadin (Warfarin) should not be taken if you are pregnant or could become pregnant during the course of treatment. Consult with your doctor if you are pregnant or breastfeeding.

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What Are the Effects of Coumadin?

Because Coumadin prevents blood clotting, patients taking Coumadin are at increased risk for bleeding and bruising. People taking Coumadin must have routine blood testing in order to monitor its effect as well as minimize risks of bleeding.

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What is the Blood Test that I Need?

Patients' bleeding problems are reduced through the close monitoring of a blood test, the Prothrombin time/International Normalized Ratio (PT/INR). This blood test measures how long it takes for your blood to clot. Based on the PT/INR test result, the Coumadin dose will be adjusted carefully to fit your medical condition. Patients will continue to have their PT/INR checked on a regular basis as long as they continue taking this medication.

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How Do I Have the Prothrombin Time/International Normalized Ratio (PT/INR) Checked?

If you are taking Coumadin, your health care provider will make arrangements at the time you go home for your next PT/INR blood test. These results will be reported to your doctor the same day. After having this blood test drawn, call your doctor's office as directed to receive the results. Your doctor may want to change the dose of Coumadin you are taking. Continue taking Coumadin as directed by your doctor. This gives your doctor time to evaluate the PT/INR blood test and contact you, if he/she needs to adjust your Coumadin dosage.

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What Other Medications Should I Avoid Taking that Affect Blood Clotting?

Medications that alter blood clotting such as Aspirin, Plavix (Clopidogrel), Advil (Ibuprofen), or Motrin (Ibuprofen), can prolong bleeding times and interact with Coumadin. Take them only if ordered by your doctor. Most patients can take Tylenol (Acetaminophen) for pain, if needed. Many antibiotics and other medications interact with Coumadin and increase your risk of bleeding. Always check with your doctor or pharmacist before taking any new medication.

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Special Precautions With Coumadin

  • Call your doctor immediately if you have any bleeding or bruising.

  • Do not take ANY prescriptions or over-the-counter medications, including vitamins and herbal preparations (especially those containing Vitamin E or Vitamin K), unless ordered by your doctor. Many of these medications may interact with Coumadin.

  • If you forget a pill, don’t take another to "catch up." Call your doctor for directions.

  • Tell your doctors, dentist, and pharmacist that you take Coumadin, especially before starting a new medication or having a medical or surgical procedure.

  • Try to maintain a consistent diet. Do not dramatically vary your dietary intake of foods high in Vitamin K, as these foods can interfere with how you process Coumadin. These foods include: liver, broccoli, cabbage, cauliflower, spinach, lentils, chickpeas (garbanzo beans), turnip greens, soybean oil, seaweed, green tea, and herbal teas which contain coumarin.


Produced by the Center for Patient and Community Education in association with the Department of Outcomes Management at California Pacific Medical Center. Date:11/04

References: Lexi-Comp Inc. (1978-2004). Coumadin (Wafarin). Retrieved November 14, 2004 from www.crlonline.com/crlonline. Opie, L. (2001). Drugs for the Heart (pp. 296-302). Philadelphia: WB Saunders Company.

© 2004-2008 California Pacific Medical Center

Funded by: A generous donation from the Mr. and Mrs. Arthur A. Ciocca Foundation.

Note: This information is not meant to replace any information or personal medical advice which you get directly from your doctor(s). If you have any questions about this information, such as the risks or benefits of the treatment listed, please ask your doctor(s).
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