Pulmonary embolism

Expert reviewer, Dr Richard Russell, Respiratory Consultant
Next review due March 2023

A pulmonary embolism is a blockage of a blood vessel in your lungs. It’s a serious and potentially life-threatening condition.

The most common cause of a pulmonary embolism is when a blood clot breaks off from a deep vein thrombosis (blood clot) in your leg. The clot travels through your body in your bloodstream until it gets to your lungs, where it gets stuck.

An image showing where a pulmonary embolism occurs

Symptoms of pulmonary embolism

The symptoms of pulmonary embolism are described below. If you have severe symptoms, including difficulty breathing and chest pain, you should call an ambulance and get medical help as soon as you can.

When you have a pulmonary embolism, the symptoms can sometimes be vague and nagging for several weeks, or they can be sudden and severe. Some people have few, if any, symptoms. This can sometimes make it hard for doctors to diagnose.

Symptoms may include:

  • pain in your chest
  • feeling short of breath
  • feeling faint or fainting
  • coughing up blood

The symptoms you have and how severe they are may depend on how big the pulmonary embolism is and where it is. For example, if the clot is small and in a blood vessel at the outer edge of your lungs, you may have mild symptoms. If the blood clot is large and in a central blood vessel, it could cause you to collapse suddenly.

These symptoms could be caused by conditions other than a pulmonary embolism, but if you have any of them, see your GP as soon as possible.

Diagnosis of pulmonary embolism

If your GP suspects you may have a pulmonary embolism, they’ll probably arrange for you to go to hospital for assessment as soon as possible. It may well be that you’re in hospital (after an operation, for example) when the symptoms occur.

At hospital, you may have the following tests.

  • Computed tomography pulmonary angiogram (CTPA). This is a CT scan where you have dye injected into your bloodstream to see if there’s a blockage in the arteries to your lungs.
  • Isotope lung scanning (also called ventilation-perfusion or V/Q scanning). You may be offered this test if you’re pregnant, have kidney problems or can’t have a CTPA. It shows how much blood and air are getting into your lungs.
  • A blood test called D-dimer. If the test result is negative, this may help to rule out DVT and a pulmonary embolism.
  • A leg vein ultrasound. This uses sound waves to look at your blood as it flows through the blood vessels in your legs.

Your doctor may do other tests such as a chest X-ray, an ECG and blood tests, to confirm whether you have a pulmonary embolism or another condition.

Treatment of pulmonary embolism

If you have a pulmonary embolism, it’s important that it’s treated quickly. This means that you’ll usually begin treatment while you’re waiting for tests, or for test results. You may need to be admitted to hospital, if you’re not already in hospital. You may be given oxygen to help you breathe, and fluid through a drip if necessary.

The main treatment for pulmonary embolism is a type of medicine called an anticoagulant. You may also need treatment to get rid of the existing clot.


Anticoagulants prevent blood clots forming or stop blood clots getting bigger. Which type of anticoagulant your doctor recommends will depend on a number of things. These include how serious your pulmonary embolism is and your general health, as well as local guidelines and your doctor’s own experience.

Some anticoagulant medicines are given by injection and some are given orally (by mouth) as tablets. If you have a pulmonary embolism, your doctor will probably recommend you have an injection of an anticoagulant called heparin, then start taking anticoagulant tablets.

There are two main types of oral anticoagulant medicines:

  • direct oral anticoagulants (DOACs), such as apixaban, dabiogatran, edoxaban and rivaroxaban
  • warfarin

Direct oral anticoagulants may be the first option your doctor recommends. These medicines have the advantage that you don’t need to be monitored as closely as with older anticoagulants like warfarin.

If you’re taking warfarin, you’ll need to have regular blood tests to make sure the medicine is having the correct blood thinning effect. This is called an international normalised ratio (INR) test. You won’t need to be monitored in this way if you’re taking a DOAC.

After a pulmonary embolism, you’ll need to keep taking anticoagulants for at least three months. Depending on your medical history and why you developed a pulmonary embolism, your doctor may recommend you continue taking anticoagulants for the long term. This is to prevent any more blood clots developing.

If you’re taking an anticoagulant, your nurse or doctor should give you an anticoagulant information booklet and an alert card, which you should always carry with you.

Treatments to remove clots

If your doctor thinks you have a life-threatening pulmonary embolism, you may need treatment to remove it. You may be given a type of medicine called a thrombolytic. These help to dissolve the blood clots.

If you are seriously unwell with life-threatening blood clots or other treatments haven’t worked, your doctor may suggest an operation to remove the blood clot. This is called an embolectomy. There are several different ways in which this can be performed. You can have open surgery, where the clot is taken out by making a cut in the blood vessel. Or you can have an embolectomy using a catheter. This is when a thin tube is placed inside your vein and moved to where the clot is. Your surgeon can then break up the clot via the catheter and remove it.

Causes of pulmonary embolism

Most pulmonary embolisms come from a deep vein thrombosis (DVT). This is a blood clot in your leg or your pelvis. If the blood clot moves or bits of it break off and travel to your lungs, it’s called a pulmonary embolism.

There are certain things known to be associated with developing a blood clot. These include:

  • being inactive for long periods of time; for example, if you’re recovering after a big operation or are sitting still during a long journey
  • having blood that clots more easily; for instance, if you’re overweight, pregnant or are taking the contraceptive pill
  • having cancer
  • if your blood vessels are damaged from an injury or operation

For more information about the risks of travel and pulmonary embolism, see our FAQ on flying below.

Prevention of pulmonary embolism

Preventing pulmonary embolism in hospital

If you're in hospital for a big operation or because of illness, you may be more likely to develop a deep vein thrombosis or a pulmonary embolism. When you’re in hospital, your nurse or doctor will measure your risk of developing a blood clot. You may be asked to do the following.

  • Drink plenty of fluids. If you can’t drink, you’ll be given fluids through a drip.
  • Get up and start moving about as soon as you can after an operation or illness.
  • Wear compression stockings to help your circulation.
  • Use an intermittent pneumatic compression device. This is an inflatable cuff wrapped around your leg or foot and an electrical pump that inflates it, squeezing your deep veins.
  • Have anticoagulant medicines such as heparin.

Inferior vena cava (IVC) filters

These are small metal devices used to prevent you getting a pulmonary embolism if you have a DVT. Most people with DVT can have treatment with anticoagulants. But if you can’t or you’re at high risk of a pulmonary embolism, your doctor may suggest you try an inferior vena cava (IVC) filter. An IVC filter is placed inside a vein to trap any clots before they can travel to your heart and lungs. These filters are usually temporary.

Reducing risks of pulmonary embolism when travelling

You can find out about the risks of getting a DVT or pulmonary embolism when travelling from our FAQ on flying below.

There are some simple steps you can take to reduce your chances of getting a blood clot when you’re flying.

  • Get up and walk around whenever you can.
  • Wear loose-fitting clothing.
  • Do leg exercises in your seat; for example, bend and straighten your knees, feet and toes every half hour.
  • Drink enough water so you don’t become dehydrated, and don’t drink excessive amounts of alcohol.

If you’ve had recent surgery, have had a blood clot before or have other health problems that make developing a clot more likely, speak to your GP. They may suggest you wear compression stockings or flight socks while travelling.

If you develop a painful and swollen leg or any breathing problems after a long journey, get medical advice as soon as you can. Be aware that it can take hours, days or even weeks before you notice anything.

Pulmonary embolism and pregnancy

You’re four or five times more likely to develop a blood clot (DVT and pulmonary embolism) if you're pregnant. You also have a greater chance of having a pulmonary embolism just after you’ve had your baby, especially if you’ve had a caesarean section.

There are some anticoagulants (medicines that prevent your blood clotting) that may harm a developing baby, so you shouldn't take these when you're pregnant. These include warfarin and direct oral anticoagulants. See our treatment section above for descriptions of these medicines. If you’re taking warfarin or other anticoagulant tablets, and think that you might be pregnant, tell your doctor immediately.

If your doctor thinks you're at high risk of getting a blood clot, they may offer you heparin injections while you’re pregnant. Heparin is safe to take when you’re pregnant because it doesn’t pass from you to your baby. You may need to take anticoagulant medicines for at least six weeks after you have your baby.

Frequently asked questions

  • The likelihood of developing a pulmonary embolism if you’re a young woman is very small. The chances of getting one if you’re taking the combined hormonal contraception pill are also very small, but they are greater than if you’re not taking it. However, you’re less likely to get a pulmonary embolism if you’re taking the pill, than you are if you’re pregnant.

    There are other things that increase your chances of getting a pulmonary embolism. These include your age, whether or not you’re overweight and if you have a family history of blood clots. Your doctor will discuss this before prescribing the contraceptive pill and may suggest other types of contraception for you.

  • If you travel long distances, and spend more than about four hours sitting down, then you could be more likely to develop deep vein thrombosis (DVT). This is especially true of travel by plane, where the risk of DVT is doubled or trebled after about four hours. A DVT can then lead to a pulmonary embolism. The risk of a DVT is not large – it’s thought that around one person in 6,000 gets one after a long-haul flight. The longer the journey, the greater your chances of getting a blood clot.

    People who get a DVT or pulmonary embolism after a long journey often have other health conditions or risk factors too. These include having had a previous blood clot, being very overweight or having recently had surgery. You may also be more likely to develop a blood clot if you’re pregnant or had a baby in the last six weeks.

    See our section on Prevention above for tips on how you can reduce your risk of getting blood clots when travelling.

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Related information

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  • Reviewed by Dr Kristina Routh, Freelance Health Editor, Bupa Health Content Team, March 2020
    Expert reviewer, Dr Richard Russell, Respiratory Consultant
    Next review due March 2023