Pulmonary embolism: Treatment with anticoagulants

Photo of a patient and doctor at the hospital

Pulmonary embolism is treated with anticoagulants (medication to prevent blood-clotting). This medication lowers the risk of severe illness. One possible side effect is bleeding.

Anticoagulants are a type of medication that slow down the blood-clotting process (coagulation). They are used to stop existing blood clots growing and new ones forming. They also help the body shrink blood clots and break them up. Depending on the person’s risk, anticoagulants are sometimes prescribed for long periods to prevent further pulmonary embolisms.

What types of anticoagulants are used to treat pulmonary embolism?

The following anticoagulants can be used to treat acute cases of pulmonary embolism:

Table: Anticoagulants commonly used to treat pulmonary embolism
Anticoagulant Form of use Regular blood tests needed Important characteristics
Heparin comes in low-molecular-weight (LMWH) and high-molecular weight or unfractionated (UFH) form. LMWH is most commonly used.
Injected under the skin (subcutanoeus) or into a vein
Not for LMWH
  • Fast-acting
  • LMWH is suitable during pregnancy
Fondaparinux Injected under the skin No
  • Fast-acting
Vitamin K antagonists (sometimes called coumarins) like warfarin or phenprocoumon (Marcumar or Falithrom). Tablet
  • Unreliable effect for the first few days
  • Taken in combination with heparin to start with
  • Known to interact with several drugs
Direct oral anticoagulants (DOACs) like apixaban ("Eliquis"), edoxaban ("Lixiana"), rivaroxaban ("Xarelto") and dabigatran ("Pradaxa") Tablet No
  • Fast-acting

Acute pulmonary embolism is often treated with heparin for the first few days. Once the person's condition is stable, treatment is usually continued with direct oral anticoagulants (DOACs). It is also possible to give certain types of DOAC right from the start, without using heparin. Vitamin K antagonists can be used to continue the treatment after the first few days too.

Why are direct oral anticoagulants often the medication of choice?

For a long time, vitamin K antagonists (also known as coumarins) were the standard medication for treating pulmonary embolism. But they have some disadvantages, one of which is that they interact with several other drugs. So they are not suitable for all pulmonary embolism patients.

Another issue is that it’s difficult to get the dose right. So regular blood tests have to be done to check whether the medication is actually preventing clotting. Vitamin K antagonists also take a few days to have an effect because they stop blood clotting via an indirect method. That is why they are combined with heparin or fondaparinux to start with.

Unlike vitamin K antagonists, direct oral anticoagulants prevent blood-clotting directly. They are easy to dose and there’s no need for regular blood tests to check their effect on the blood-clotting process. DOSCs are taken in tablet form and the dose is fixed. It's enough to have the dose checked occasionally. They interact less with other drugs too.

Generally speaking, the choice of anticoagulant mainly depends on whether the person has any other medical conditions, and what they are. Ease of use is one of the other factors. Pregnant women are always given a low-molecular-weight heparin because it doesn’t get passed on to the unborn child via the placenta.

How effective are anticoagulants?

Anticoagulants like heparin, fondaparinux, vitamin K antagonists and DOACs are effective treatments for pulmonary embolism. They can ease the symptoms and prevent complications. The research results for the latest DOACs were not worse than for vitamin K antagonists or heparin, which have been in use for many years.

Anticoagulants are taken for at least three months. Then a decision can be made about whether it makes sense to take them for longer in order to prevent other pulmonary embolisms in the future.

What are the possible side effects and complications?

All anticoagulants increase the likelihood of bleeding. If you’re taking them, there are various ways to prevent bleeding or detect it at an early stage. That includes looking for signs like blood in your stool, bruising, or heavy nosebleeds. If you’re scheduled for surgery, it’s also a good idea to tell the doctors you’re using anticoagulants. That way, you can stop taking them in time for the operation.

Heavy bleeding is a rare but serious complication of taking anticoagulants. It needs to be treated quickly. The risk of bleeding is highest in the first few weeks of treatment.

Heavy bleeding becomes more likely as the dosage increases. Other risk factors include age and taking other anticoagulants at the same time. These could be things like acetylsalicylic acid (the drug in medicines like Aspirin), clopidogrel or non-steroidal (NSAIDs) like ibuprofen. Chronic kidney or liver disease, blood-clotting disorders and cancer all increase the risk of bleeding too.

It is a good idea to carry a medical ID card (in German: Medikamentenpass). It includes information about the anticoagulants you’re taking and the dosage. In an emergency, like an injury or accident, a medical ID card is a quick way for medical staff to see what action needs to be taken.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Created on December 15, 2022

Next planned update: 2025


Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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