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My goal INR range is_____to_____


You have been prescribed warfarin (Coumadin® or Jantoven®) to help prevent blood clots. You must follow your doctor or healthcare provider’s instructions carefully in  order to prevent bleeding or the formation of serious blood clots.

Warfarin is known as an anticoagulant which is a drug that lengthens the time it takes for your blood to clot.  This makes it harder for clots to develop in your blood vessels and heart, and stops existing clots from getting larger.  If you are going to be taking warfarin, there are some important facts you need to know about this medication.

Important facts to remember…

  • Take the exact amount prescribed at the same time each day. If you miss a dose, take it as soon as you remember—unless it’s almost time for your next dose. DO NOT take more pills to “catch up.”

  • Call your doctor if you forget to take one or more doses. DO NOTstop taking warfarin without your doctor or healthcare provider’s approval.

  • Make sure to keep all appointments for blood related laboratory tests (PT/INR) as your doctor needs to check them to see if the medication is working for you and to check for side effects.

  • Remember to tell your surgeon or dentist that you are taking warfarin.  You may need to stop taking it ahead of time if you need to have dental work or a surgical procedure.

Call your doctor or healthcare provider immediately if you…

  • Have any bleeding or bruising that is NOT normal. Tell your doctor or healthcare provider if you have ANY of the following: dark, bloody or tarry stools, red or rust color urine, bleeding gums, nose bleeds, easy bruising, unusual weakness, or vomiting/coughing up blood.

  • Have any diarrhea, dizziness, purple discoloration of your toes or fingers, swollen lips, tongue, throat or face, hives or painful rash, or yellowing of the skin or eyes (jaundice). These may be serious side effects of warfarin that require immediate medical attention.

  • Have any abdominal pain, severe chest pain or shortness of breath, headache, eye problems (blurred vision/loss of vision), or severe leg pain (calf or thigh). These may be a sign of a blood clot.

  • Start any new medications, including over-the-counter (OTC) products or dietary supplements, such as acetaminophen (Tylenol®), aspirin, ibuprofen (Advil®), naproxen (Aleve®), or herbal products (Danshen, Don Quai, Ginseng, St. John’s Wort); warfarin interacts with many of these products. Talk to your doctor, pharmacist or healthcare professional about which of your current medications may interact with warfarin.

  • Are NOT able to eat or eat less than usual because of abdominal pain or decreased appetite.

  • Become pregnant or plan to do so in the near future.  Warfarin can harm your unborn child.



Foods that contain vitamin K may affect how warfarin works in your body. Always remember to… 

  • BE CONSISTENT in the amount of vitamin K in your diet each day.

  • Avoid binge drinking; however, a small amount of alcohol (1 oz. liquor, 4 oz. wine, or 12 oz. beer per day) should be safe. Talk to your doctor or healthcare professional for more information.

  • Tell you doctor or healthcare provider if you’re taking Vitamin E supplements, fish oil supplements, garlic, ginger, licorice, or turmeric supplements;  or any multivitamin or supplement containing Vitamin K; these all may affect blood clotting.


Foods High in Vitamin K

(This list is NOT all encompassing.  Talk to your healthcare provider or dietician to learn the exact vitamin K content of your food.)


Dark green leafy vegetables  




Greens (collard, turnip, beet, mustard, dandelion)                  

Brussels sprouts


Green onions or  scallions                                                                                    


 Why do I need to take this medication?

Clots may form in blood vessels and travel to the lungs or brain where they can become stuck and cause harm to you.  Warfarin


has been prescribed for you because you have a condition or conditions that increase your chance of forming blood clots.  Some of these conditions include:

  • Heart failure

  • Irregular heart beat

  • Artificial heart valve

  • Recent heart attack

  • Current or previous clot in the leg or clot in the lung

  • Certain types of heart disease

 How long will I have to take this medication?

Weeks, months, or years, depending on your condition and how long your doctor or healthcare provider thinks you’ll be at risk for forming blood clots.

What is a PT/INR test?

A blood tests to see how many seconds it takes for a clot to form in your blood.  This is know as your prothrombin time (PT) and is converted into the INR, a standardized number used to make sure your warfarin dose is right for you.  Your blood will be tested frequently when you first start taking warfarin and then routinely while you are taking warfarin.  This is necessary because many things can change the way warfarin works in your body.  If your PT/INR changes, your dose of warfarin also will need to change to make sure the medication is working for you and to check for side effects. 

What side effects may occur?

The most serious side effect of warfarin is bleeding. Some signs to watch out for:

  • Bleeding, that takes a long time to stop from a minor injury such as a cut, or bleeding from your gums or nose

  • A lot of bruising or unexplained bruising

  • Red or rust-colored urine

  • Black or tarry stools, or blood in the stool

  • Purple-blue coloring of the toes or fingers

  • Dizziness or faintness

  • Women: long lasting or a lot of menstrual or vaginal bleeding

Let your doctor or healthcare provider know immediately if you have any of these symptoms.

How can I lower my risk of bleeding?

Since it takes longer for your blood to clot when you are taking warfarin, you will need to take some steps to avoid injury:

  • Do NOT take part in activities that have a high risk of injury, such as skiing, football, or other contact sports

  • Shave with an electric razor instead of a blade.

  • Use a soft-bristled toothbrush and floss gently with waxed floss.

  • Do NOT walk barefoot and do NOT trim corns or foot calluses yourself.

  • Tell your dentist or orthodontist that you are taking warfarin

If you have additional questions about warfarin, please talk to your nurse so arrangements can be made for a pharmacist to meet with you.



-Bristol- Myers Squibb Co. Coumadin® package insert. Princeton, NJ; August 2007.                                                                              

-Micromedex® Healthcare Series [Internet database] Greenwood Village, Colo: Thomson Healthcare. Updated periodically.

USDA Nutrient Database for Standard Reference, Release 21

K-Card (Couris and Dwyer, 1997). September, 2009


Information provided as a service of University Medical Center at Princeton's Department of Pharmacy Services                          

 Revised:May 2010

The health information provided in this publication is for general education purposes and is not intended to constitute medical advice. The information should not be used for diagnosis or treatment, nor should it be used to replace the advice of licensed healthcare professionals. Health concerns or questions should be discussed with your physician. If you have concerns about your health, please contact your healthcare provider.