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What is warfarin and how does it work?

Warfarin is a prescription medicine that helps stop abnormal blood clots from forming or growing larger in blood vessels. Because clots can block blood flow, they can cause a heart attack, brain attack (stroke), and other serious problems.


While you're taking warfarin, you must have regular blood tests to make sure you're getting enough warfarin to stop harmful clots but not so much that your blood won't clot when it should (for example, when you cut yourself).


How do I take warfarin?

Because warfarin increases your risk for bleeding, you must take it exactly as your healthcare provider tells you. You'll have to get a blood test called a PT/INR at least once a month, sometimes more often. (PT/INR stands for prothrombin time and international normalized ratio.) The amount of warfarin you take may change depending on test results.


Follow these guidelines when taking warfarin:


* Take warfarin at the same time each day.


* If you miss or forget a dose, call your healthcare provider for advice. Don't take a double dose.


* Don't take warfarin if you're pregnant or may become pregnant; if you want to breastfeed, you need to discuss it with your healthcare provider first.


* Tell all your other healthcare providers, including your dentist, that you're taking warfarin. If you need surgery, medical tests, or dental procedures, you may have to stop taking warfarin temporarily.


* Talk to your healthcare provider before you take any new medicine, including over-the-counter drugs, herbal supplements, and vitamins.


* Call your healthcare provider right away if you have any signs of unusual bleeding or bruising such as bleeding from a cut that doesn't stop, bleeding gums, pink or brown urine, red or dark-colored stool, heavier-than-normal menstrual bleeding or abnormal vaginal bleeding, a nosebleed, or coughing up or vomiting blood or material that looks like coffee grinds. Also call your healthcare provider or 911 if you have a severe headache, a fever or illness that gets worse, dizziness or weakness, chest pain, or trouble breathing, or if you have new pain or color or temperature changes in any part of your body, such as your toes. Go to a hospital emergency department if you hit your head to make sure you don't have any bleeding in your brain.



Do I have to change my diet?

Eat a normal balanced diet, and don't make changes in your diet without first talking to your healthcare provider. Foods rich in vitamin K (dark green or leafy vegetables such as broccoli and spinach) can change the effects of warfarin in your body. You don't have to avoid these foods, but try to keep the amount you eat the same every week. Don't drink alcohol, and avoid drinking cranberry juice or eating cranberry products because they can affect how warfarin works in your body.


How can I reduce my risk of bleeding?

Because you may bleed easily, take these precautions:


* Clean your teeth gently with a soft-bristle toothbrush and waxed floss.


* Shave with an electric razor instead of a razor blade, or use hair-removing cream.


* Take care not to cut yourself when using knives and other sharp objects.


* Don't walk barefoot, and avoid activities that have a risk of injury, such as contact sports.



If you start bleeding, apply constant pressure until the bleeding stops. If it doesn't stop in 10 minutes, call your healthcare provider or 911 for help.