Normally, when an injury that causes
bleeding occurs, the body sends out signals that cause blood to clot at the
wound, and then the clot naturally breaks down as the wound heals. A person prone to
abnormal clotting has an imbalance between clot formation and clot breakdown.
Warfarin prevents new clots from forming and
prevents existing clots from growing by stopping the production of certain
proteins that are needed for blood to clot. Warfarin does not break up or dissolve
existing blood clots. Warfarin is a type of anticoagulant medicine.
Warfarin is used to prevent or treat
deep vein thrombosis and
If you have a high risk of these problems, such as having a recent surgery, you might take warfarin for a short time, about a few weeks.
If you have had deep vein thrombosis or pulmonary embolism, you might take warfarin for a longer time, such as 3 months or longer. The
length of time will vary based on your health.
Warfarin reduces the chance that a
new blood clot will form or that an existing blood clot will get larger.
All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.
Here are some important things to think about:
or other emergency services right away if:
Call your doctor right away if:
If you are injured, apply pressure to stop the bleeding. Realize that it
will take longer than you are used to for the bleeding to stop. If you can't get the bleeding to stop, call your doctor.
or other emergency services right away if you have:
Call your doctor if you have:
Other side effects of warfarin include:
See Drug Reference for a full list of side effects.
(Drug Reference is not available in all systems.)
When you take warfarin, you need to take extra steps to avoid bleeding problems.
For more information, see:
what to do if you miss a dose of anticoagulant.
Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.
There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.
If you are pregnant, do not take warfarin. Warfarin can cause miscarriage or birth defects. If you are taking warfarin, talk to your doctor about how you can prevent pregnancy.
If you think you might be pregnant: Call your doctor. If you are pregnant, you will take heparin during your pregnancy.
If you plan on getting pregnant: Talk with your doctor. You and your doctor will decide which medicine you will take—warfarin or heparin—while trying to get pregnant.
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 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.
Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.
Antithrombotic drugs (2011). Treatment Guidelines From The Medical Letter, 9(110): 61–66.
May 14, 2012
E. Gregory Thompson, MD - Internal Medicine
& Jeffrey S. Ginsberg, MD - Hematology
How this information was developed to help you make better health decisions.
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