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Pulmonary embolism

Read about how pulmonary embolisms are treated using anticoagulant medicines and, occasionally, surgery to remove the blockage.

The main treatment for a pulmonary embolism is an anticoagulant, a type of medication that stops your blood clotting easily.

The anticoagulant will prevent the clot getting larger while your body slowly absorbs it. It also reduces the risk of further clots developing.

In some cases, other treatments may be needed to remove or break up the clot. This can be done with medication called thrombolytics or, less commonly, surgery.

About half of all cases of pulmonary embolism occur in hospital. If you're not already in hospital, you'll be admitted so you can receive treatment. If necessary, you'll be given oxygen to help you breathe more comfortably.


Anticoagulants are often referred to as blood-thinning medicines, although they don't actually thin the blood. Instead, they alter chemicals in the blood to prevent clots forming easily.

The main anticoagulants used to treat pulmonary embolisms are heparin and warfarin.


Heparin is given as an injection. Regular injections of this medication are usually used as the initial treatment for a pulmonary embolism because they start working immediately.

Most people diagnosed with a pulmonary embolism will initially need injections of heparin for at least five days. You'll then usually continue taking warfarin only.

Heparin can cause side effects, including:


If you're diagnosed with a pulmonary embolism, you'll usually start taking warfarin tablets after you've have the initial injections of heparin.

Warfarin takes longer to start working than heparin injections, but as it's more convenient to take, it's usually recommended for a longer period after you stop having the injections.

Treatment with warfarin will usually be recommended for at least three months, although some people need to take it for longer than this. Occasionally, warfarin may need to be taken for the rest of your life.

The effects of warfarin vary from person to person, so you'll need to be closely monitored and have regular blood tests to check you're taking the right dosage. These tests can usually be carried out on an outpatient basis, which means you won't need to stay in hospital.

You may need two or three blood tests a week when you first start taking warfarin until the correct dose is determined. After this, you may only need to have a blood test about once a month.

There are several factors that can alter the effectiveness of warfarin, including your diet, other medications you're taking and how well your liver is working.

Therefore, while taking warfarin you should: 

  • try to keep your diet consistent
  • limit your alcohol consumption and avoid drinking more than the recommended amounts (three to four units a day for men and two to three units a day for women)
  • take your medication at the same time each day
  • avoid taking any other medicine without first checking with your GP, pharmacist or anticoagulant specialist
  • avoid taking herbal medicines

Warfarin can cause a wide range of side effects, including:

  • bleeding problems
  • headaches
  • diarrhoea
  • nausea and vomiting 
  • jaundice (yellowing of the skin and whites of the eyes)

Read more about warfarin.


Dabigatran is an oral anticoagulant that specifically targets thrombin (a protein that helps blood clots form). It's used to treat and prevent deep vein thrombosis (DVT) and pulmonary embolism in adults.

The recommended dosage of dabigatran will depend on your age and whether you're taking other medication for other health conditions. Dabigatran isn't recommended for people with severely reduced kidney function.

Bleeding and indigestion are the most common side effects of dabigatran.

Read the National Institute for Health and Care Excellence (NICE) guidance about dabigatran for the treatment and secondary prevention of deep vein thrombosis and pulmonary embolism (PDF, 255kb).


Rivaroxaban is another medication that can be used to treat and prevent DVT and pulmonary embolism in adults.

The recommended dosage of rivaroxaban will depend on whether it's being used to treat pulmonary embolism for the first time or a recurrence of the problem. How long treatment lasts will depend on a person's bleeding risk and other clinical criteria.

Side effects of rivaroxaban can be varied and may include anaemia, dizziness, headache, fainting, rapid heartbeat (tachycardia), low blood pressure, diarrhoea, constipation and swelling, particularly of the ankles and feet (oedema).

Read the NICE guidance about rivaroxaban for treating pulmonary embolism and preventing recurrent venous thromboembolism (PDF, 233kb).


Apixaban is another anticoagulant that's recently been approved by NICE to treat and prevent DVT or pulmonary embolism.

It's taken orally (in tablet form) twice a day for the first seven days. The dosage is then halved and taken twice a day for at least three months.

The most common side effects of apixaban are bleeding, bruising, nausea and anaemia. It's also recommended that apixaban should be used with caution in people with severe kidney problems.

You can read more about apixaban for the treatment and secondary prevention of deep vein thrombosis and pulmonary embolism (PDF, 228kb).

Special considerations

If you're pregnant, you'll be given regular heparin injections instead of warfarin tablets for the full length of your pregnancy. This is recommended because taking warfarin tablets while you're pregnant could harm your baby.

If you have cancer, you'll usually be given heparin injections instead of warfarin tablets for six months or until the cancer is cured. Evidence suggests that regular injections are more effective than warfarin tablets in these cases.

Removing the blockage

In more severe cases of pulmonary embolism, treatment may be needed to remove the blockage. This is often achieved using injections of a type of medication called a thrombolytic, such as alteplase, which breaks up the blood clot.

A newer procedure may also be used called ultrasound-enhanced, catheter-directed thrombolysis. It involves using high-frequency, low-energy ultrasound waves in combination with thrombolytic medication to dissolve the blood clot. The procedure usually lasts for 12-24 hours and you'll be continuously monitored throughout the duration of the treatment.

Read NICE guidelines on ultrasound-enhanced, catheter-directed thrombolysis for pulmonary embolism (PDF, 136kb)

Occasionally, a surgical procedure called an embolectomy may be used to treat a pulmonary embolism. This is where a surgeon makes a cut in the pulmonary artery and the blockage is sucked out. However, this is a major operation so it's usually only recommended in particularly severe cases or if other treatments are unsuitable.

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