Health Topic

Pulmonary Embolism

A pulmonary embolism is a sudden blockage in a lung artery. The cause is usually a blood clot in the leg called deep vein thrombosis. Learn more.

Reviewed Reviewed by a registered pharmacistGeneral information

Also called: Blood clots in the lung

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Pulmonary Embolism

A pulmonary embolism (PE) is a sudden blockage in a lung artery. It usually happens when a blood clot breaks loose and travels through the bloodstream to the lungs. PE is a serious condition that can cause:

  • Permanent damage to the lungs
  • Low oxygen levels in your blood
  • Damage to other organs in your body from not getting enough oxygen

PE can be life-threatening, especially if a clot is large, or if there are many clots.

The cause is usually a blood clot that breaks loose and travels through the bloodstream to the lungs. The clot is usually a deep vein thrombosis (DVT), a clot in the leg. In rare cases, material such as air bubbles, clumps of fat, or parts of a tumor can block the lung artery and cause PE.

Anyone can get a pulmonary embolism (PE), but certain things can raise your risk of PE:

  • Having surgery, especially joint replacement surgery.
  • Certain medical conditions, including
  • Cancers
  • Heart diseases
  • Lung diseases
  • A broken hip or leg bone or other trauma

Symptoms of PE include:

  • Shortness of breath
  • Rapid breathing
  • Chest pain or discomfort, which usually gets worse when you cough or take a deep breath
  • Increased heart rate
  • Coughing up blood
  • Very low blood pressure, lightheadedness, or fainting

Sometimes people with PE don't have any symptoms until they have serious complications, such as pulmonary hypertension (high blood pressure in the arteries to your lungs).

It can be difficult to diagnose PE. To find out if you have a PE, your health care provider will:

  • Take your medical history, including asking about your symptoms and risk factors for PE
  • Do a physical exam
  • Likely order some tests, including various imaging and blood tests

If you have PE, you need medical treatment right away. The goal of treatment is to break up clots and help keep other clots from forming. Treatment options include medicines and procedures.

  • Anticoagulants, or blood thinners, keep blood clots from getting larger and stop new clots from forming. You might get them as an injection, a pill, or through an I.V. (intravenous). They can cause bleeding, especially if you are taking other medicines that also thin your blood, such as aspirin.
  • Thrombolytics are medicines to dissolve blood clots. You may get them if you have large clots that cause severe symptoms or other serious complications. Thrombolytics can cause sudden bleeding, so they are used if your PE is serious and may be life-threatening.
  • Catheter-assisted thrombus removal uses a flexible tube to reach a blood clot in your lung. Your health care provider can insert a tool in the tube to break up the clot or to deliver medicine through the tube. Usually you will get medicine to put you to sleep for this procedure.
  • A vena cava filter may be used in some people who cannot take blood thinners. Your health care provider inserts a filter inside a large vein called the vena cava. The filter catches blood clots before they travel to the lungs, which prevents pulmonary embolism. But the filter does not stop new blood clots from forming.

Preventing new blood clots can prevent PE. Prevention may include:

  • Continuing to take blood thinners. It's also important to get regular checkups with your provider, to make sure that the dosage of your medicines is working to prevent blood clots but not causing bleeding.
  • Heart-healthy lifestyle changes, such as heart-healthy eating, exercise, and, if you smoke, quitting smoking.
  • Moving your legs when sitting for long periods of time (such as on long trips).
  • Moving around as soon as possible after surgery or being confined to a bed.

It sits within Lungs and Breathing.

The lead U.S. institute for this subject is the National Heart, Lung, and Blood Institute.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Pulmonary Embolism

989 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

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Diagnosis and Tests

Treatments and Therapies

Related Issues

Statistics and Research

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Pulmonary Embolism. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Pulmonary Embolism, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.