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Warfarin is a medicine that you take to prevent blood clots. It is often called a blood thinner. Doctors give warfarin (such as Coumadin) to reduce the risk of blood clots. You may be at risk for blood clots if you have atrial fibrillation or deep vein thrombosis. Some other health problems may also put you at risk.
Warfarin slows the amount of time it takes for your blood to clot. It can cause bleeding problems. Even if you've been taking warfarin for a while, it's important to know how to take it safely.
Foods and other medicines can affect the way warfarin works. Some can make warfarin work too well. This can cause bleeding problems. And some can make it work poorly, so that it does not prevent blood clots very well.
You will need regular blood tests to check how long it takes for your blood to form a clot. This test is called a PT or prothrombin time test. The result of the test is called an INR level. Depending on the test results, your doctor or anticoagulation clinic may adjust your dose of warfarin.
Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse advice line (811 in most provinces and territories) if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.
Call 911 anytime you think you may need emergency care. For example, call if:
Call your doctor or nurse advice line now or seek immediate medical care if:
Watch closely for changes in your health, and be sure to contact your doctor or nurse advice line if you have any problems.
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Current as of: September 7, 2022
Author: Healthwise Staff
Medical Review:Adam Husney MD - Family Medicine & E. Gregory Thompson MD - Internal Medicine & Martin J. Gabica MD - Family Medicine
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