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Lung Disease & Respiratory Health Center

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Anticoagulants for Pulmonary Embolism



Generic Name Brand Name
warfarin Coumadin

Direct thrombin inhibitors

Generic Name Brand Name
dabigatran Pradaxa

Factor Xa inhibitors

Generic Name Brand Name
apixaban Eliquis
Generic Name Brand Name
rivaroxaban Xarelto

Factor Xa specific inhibitors (used in the hospital)

Generic Name Brand Name
fondaparinux Arixtra

Low-molecular-weight heparins

Generic Name Brand Name
dalteparin Fragmin
enoxaparin Lovenox
tinzaparin Innohep

Unfractionated heparins

Generic Name

How It Works

Anticoagulants work by increasing the time it takes a blood clot to form. They also prevent a clot from getting bigger.

Normally, when an injury that causes bleeding occurs, the body sends out signals that cause the blood to clot at the wound. The clot naturally breaks down as the wound heals. A person who is prone to abnormal clotting has an imbalance between clot formation and clot breakdown. Anticoagulants prevent the production of certain proteins that are needed for blood to clot. Anticoagulants do not break up or dissolve existing blood clots.

Why It Is Used

In people who have had pulmonary embolism, anticoagulants are used to prevent more blood clots from forming and causing another episode of pulmonary embolism. They are used in the hospital as first treatment of a pulmonary embolism. And they also may be used at home. Treatment with anticoagulants may continue throughout your life if your risk of having another pulmonary embolism remains high.


Heparin is given as an injection. It immediately affects the clotting system in your body. It might be the first anticoagulant used to treat pulmonary embolism. You might take heparin for a few days. Then you'll likely take another anticoagulant in pill form.

  • Low-molecular-weight heparin (LMWH) as initial treatment is usually preferred because it can be given as an injection once or twice per day, and it may be given at home, which allows you to leave the hospital earlier. Blood tests are not usually needed to monitor LMWH's clotting effect.
  • Unfractionated heparin is another form that can be used. It is given in the hospital. Unfractionated heparin is usually given continuously through your vein (intravenously, or IV). But it can also be given as an injection under the skin. Frequent blood tests are used to monitor the clotting effects of this medicine.


Warfarin is taken as a pill. Warfarin is usually started while a person is still being treated with heparin because it takes several days for warfarin to build up to a level that's effective. When warfarin is at the right level in your blood, you stop taking heparin shots and keep taking warfarin pills.

Anticoagulants other than warfarin

Apixaban, dabigatran, and rivaroxaban are taken as pills. They might be started right away for treatment or right after you stop taking heparin.


Fondaparinux is an injected anticoagulant. It is used only in the hospital.

How Well It Works

Anticoagulants are effective in treating and preventing pulmonary embolism and deep vein thrombosis.1, 2, 3, 4

Side Effects

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:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Allergic reaction

Call911or other emergency services right away if you have:

Call your doctor if you have:


Call 911 or other emergency services right away if you have:

Call your doctor now or seek immediate medical care if you have:

  • Any abnormal bleeding, such as:

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.

Less serious side effects

Apixaban might cause a skin rash.

Dabigatran might cause stomach upset or stomach pain.

Heparin might cause pain, irritation, or bruising at the injection site.

Rivaroxaban does not commonly cause other side effects.

Warfarin might cause a skin rash.

Apixaban, dabigatran, and rivaroxaban are newer medicines. So doctors do not yet know if they have any other long-term side effects.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Dabigatran storage. Keep your medicine in its original container or blister pack. Do not use a pill organizer or pill box. This medicine is sensitive to moisture.5

When you take anticoagulants, you need to take extra steps to avoid bleeding problems. These steps include:

actionset.gif Warfarin: Taking Your Medicine Safely
actionset.gif Blood Thinners Other Than Warfarin: Taking Them Safely

Long-term use of heparin is not typically recommended. It requires one or two injections each day. And long-term use is linked with osteoporosis.

Taking medicine

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.

Advice for women

If you are pregnant, breast-feeding, or trying to get pregnant, talk with your doctor. You and your doctor will decide what medicines are safe for you. Do not use any medicines unless your doctor says it's okay.

If you are pregnant, tell your doctor right away. Do not take warfarin if you are pregnant. Warfarin can cause miscarriage or birth defects. You and your doctor will decide what medicines are safe for you during pregnancy. Apixaban is not recommended for pregnant women. Apixaban, dabigatran, and rivaroxaban have a risk of pregnancy-related bleeding. You might take heparin during your pregnancy. Heparin has not been shown to affect the fetus.

If you are not planning on getting pregnant, talk to your doctor about how you can prevent pregnancy.

For more information, see Pregnancy and the Increased Risk of Developing Blood Clots.


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.


  1. Agnelli G, et al. (2013). Apixaban for extended treatment of venous thromboembolism. New England Journal of Medicine, 368(8): 699-708. DOI: 10.1056/NEJMoa1207541. Accessed September 17, 2014.

  2. Kearon C, et al. (2012). Antithrombotic therapy for VTE disease. Chest, 141(2, Suppl): e419S-e494S.

  3. EINSTEIN-PE Investigators (2012). Oral rivaroxaban for the treatment of symptomatic pulmonary embolism. New England Journal of Medicine, 366(14): 1287-1297.

  4. Schulman S., et al. (2009). Dabigatran versus warfarin in the treatment of acute venous thromboembolism. New England Journal of Medicine, 361(24): 2342-2352. DOI: 10.1056/NEJMoa0906598. Accessed April 21, 2014.

  5. Spinler SA, Willey VJ (2011). A patient's guide to taking dabigatran etexilate. Circulation, 124(8): e209-e211.

ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerJeffrey S. Ginsberg, MD - Hematology

Current as ofMay 1, 2014

WebMD Medical Reference from Healthwise

Last Updated: May 01, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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