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Published on: 2/24/2026

Sudden Chest Pain? Why Pulmonary Embolisms Occur & Vital Medical Steps

Sudden chest pain with shortness of breath can signal a pulmonary embolism, a blood clot that often starts in the leg, travels to the lungs, blocks blood flow, and strains the heart; leg swelling or pain may come first. If suspected, seek emergency care now for tests like CT angiography and D-dimer and for prompt treatment with blood thinners, oxygen, or clot-busting therapy when indicated.

Risk is higher with immobility, recent surgery, cancer, estrogen use, pregnancy, smoking, obesity, heart disease, or prior clots; there are several factors to consider that can change diagnosis, treatment length, and prevention, so see the complete details below to guide your next steps.

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Explanation

Sudden Chest Pain? Why Pulmonary Embolisms Occur & Vital Medical Steps

Sudden chest pain can be frightening. While many causes are mild—such as muscle strain or acid reflux—some are serious and require urgent medical care. One of the most dangerous causes is a pulmonary embolism.

A pulmonary embolism (PE) occurs when a blood clot blocks an artery in the lungs. This can prevent oxygen from reaching parts of the lung and strain the heart. Without prompt treatment, a pulmonary embolism can become life-threatening. The good news: when recognized early, it is treatable.

This guide explains why pulmonary embolisms happen, the symptoms to watch for, and the vital medical steps you should take.


What Is a Pulmonary Embolism?

A pulmonary embolism happens when a clot—usually formed in the deep veins of the legs or pelvis—travels through the bloodstream to the lungs. This type of clot often starts as a condition called deep vein thrombosis (DVT).

When the clot lodges in a lung artery:

  • Blood flow to part of the lung is blocked
  • Oxygen levels in the blood may drop
  • The heart must work harder to pump blood
  • Lung tissue can become damaged

The severity of a pulmonary embolism depends on the size of the clot and how much of the lung is affected.


Why Do Pulmonary Embolisms Occur?

Pulmonary embolisms typically develop due to one or more of the following risk factors:

1. Blood Clots in the Legs (DVT)

Most pulmonary embolisms begin as deep vein thrombosis. Clots form in deep leg veins when blood flow slows or the blood becomes more prone to clotting.

2. Prolonged Immobility

Long periods of sitting or lying down can increase risk. Examples include:

  • Long flights or car rides
  • Extended bed rest after surgery or illness
  • Hospital stays

When the legs are still for too long, blood flow slows and clots may form.

3. Surgery or Injury

Major surgery—especially orthopedic procedures like hip or knee replacement—raises pulmonary embolism risk. Trauma to the lower body also increases clot risk.

4. Cancer and Cancer Treatments

Certain cancers and chemotherapy treatments increase the body's tendency to form clots.

5. Hormonal Factors

  • Birth control pills
  • Hormone replacement therapy
  • Pregnancy and postpartum period

Estrogen increases clotting risk.

6. Medical Conditions

Conditions that may raise pulmonary embolism risk include:

  • Obesity
  • Smoking
  • Heart disease
  • Inherited clotting disorders
  • Previous history of DVT or pulmonary embolism

Understanding your risk factors can help with prevention and early detection.


Common Symptoms of Pulmonary Embolism

Symptoms of a pulmonary embolism can vary from mild to severe. Some people have subtle signs; others experience sudden, dramatic symptoms.

Most Common Symptoms

  • Sudden chest pain (often sharp and worse with deep breathing)
  • Shortness of breath (even at rest)
  • Rapid heartbeat
  • Lightheadedness or dizziness
  • Cough (sometimes with bloody mucus)

Symptoms of Deep Vein Thrombosis (DVT)

Because many pulmonary embolisms begin in the legs, you may notice:

  • Leg swelling (usually one leg)
  • Leg pain or tenderness
  • Warmth in the affected area
  • Red or discolored skin

If you experience sudden chest pain along with shortness of breath, seek emergency care immediately.


How Serious Is a Pulmonary Embolism?

A pulmonary embolism is a medical emergency. Large clots can:

  • Block major lung arteries
  • Cause low blood oxygen levels
  • Lead to collapse or shock
  • Strain or damage the heart

However, not all pulmonary embolisms are massive. Smaller clots may cause milder symptoms but still require prompt treatment to prevent complications or recurrence.

With modern treatment, many people recover fully—especially when care is sought quickly.


Vital Medical Steps If You Suspect a Pulmonary Embolism

If you suspect a pulmonary embolism, time matters.

1. Seek Immediate Medical Care

Call emergency services or go to the nearest emergency department if you have:

  • Sudden chest pain
  • Unexplained shortness of breath
  • Fainting or near-fainting
  • Coughing up blood

Do not attempt to "wait it out."

2. Medical Evaluation

Doctors may perform:

  • A physical exam
  • Blood tests (such as D-dimer)
  • CT pulmonary angiography (a specialized scan)
  • Ultrasound of the legs
  • ECG or chest X-ray

These tests help confirm or rule out a pulmonary embolism.

3. Treatment

Treatment typically includes:

  • Anticoagulants (blood thinners): Prevent existing clots from growing and reduce new clot formation
  • Thrombolytic therapy: "Clot-busting" drugs for severe cases
  • Oxygen therapy: If oxygen levels are low
  • Rarely, surgery or catheter procedures to remove large clots

Treatment duration varies. Some people need blood thinners for three months; others may require longer therapy depending on risk factors.


Preventing Pulmonary Embolism

Prevention focuses on reducing clot risk, especially if you have known risk factors.

Practical Prevention Tips

  • Move regularly during long travel (stand, stretch, walk)
  • Stay hydrated
  • Wear compression stockings if recommended
  • Follow post-surgery mobility instructions
  • Take prescribed blood thinners exactly as directed
  • Maintain a healthy weight
  • Stop smoking

If you have a personal or family history of blood clots, speak to a doctor about prevention strategies.


When Symptoms Are Unclear

Chest pain and shortness of breath can have many causes, including:

  • Muscle strain
  • Anxiety
  • Pneumonia
  • Heart conditions
  • Acid reflux

Because symptoms overlap, it can be difficult to know what's serious. If you're experiencing chest pain or breathing difficulties and want to better understand whether your symptoms could indicate a Pulmonary Embolism, a free online symptom checker can help you assess your risk level and determine if you need urgent care.

If symptoms are severe, sudden, or worsening, seek emergency treatment immediately.


Long-Term Outlook

Most people recover from a pulmonary embolism with appropriate treatment. However, possible complications include:

  • Recurrent pulmonary embolism
  • Chronic thromboembolic pulmonary hypertension (rare but serious)
  • Ongoing shortness of breath

Follow-up care is essential. Your doctor may:

  • Adjust blood thinner medications
  • Monitor clotting levels
  • Evaluate for underlying clotting disorders

Adhering to treatment significantly reduces the risk of recurrence.


When to Speak to a Doctor

You should speak to a doctor promptly if you:

  • Have risk factors for blood clots
  • Experience leg swelling or pain
  • Notice unexplained shortness of breath
  • Develop new or persistent chest discomfort

If symptoms suggest a possible pulmonary embolism, treat it as urgent. Early action can save your life.


Final Thoughts

Sudden chest pain should never be ignored. While many causes are minor, a pulmonary embolism is one condition that requires immediate attention.

Pulmonary embolisms occur when blood clots—often from the legs—travel to the lungs and block blood flow. Risk factors include immobility, surgery, cancer, hormonal therapy, and inherited clotting disorders. Symptoms often include chest pain and shortness of breath, and prompt medical evaluation is critical.

If you are uncertain about your symptoms, consider using a Pulmonary Embolism symptom checker to evaluate your risk and help guide your next steps. Most importantly, speak to a doctor immediately about any symptoms that could be serious or life-threatening.

When recognized and treated early, pulmonary embolism is manageable. Acting quickly makes all the difference.

(References)

  • * Konstantinides SV, Meyer G, Becattini C, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS). Eur Heart J. 2020 Jan 21;41(4):543-603. doi: 10.1093/eurheartj/ehz405. Epub 2019 Aug 31. PMID: 31504429.

  • * Chaparro L, Al-Samkari H, Connors JM. Risk factors for pulmonary embolism: A systematic review and meta-analysis. Thromb Res. 2021 Jan;197:179-192. doi: 10.1016/j.thromres.2020.10.038. Epub 2020 Oct 30. PMID: 33187843.

  • * Müller-Schall T, Mücke MM, Al-Samman B, et al. Diagnosis of Acute Pulmonary Embolism. Dtsch Arztebl Int. 2022 Nov 11;119(45):760-770. doi: 10.3238/arztebl.m2022.0298. PMID: 36629731; PMCID: PMC9931707.

  • * Agnelli G, Becattini C. Pulmonary embolism: an update on diagnosis and management. J Thromb Haemost. 2022 Aug;20(8):1733-1741. doi: 10.1111/jth.15802. Epub 2022 Jun 30. PMID: 35770511.

  • * Lombardi R, Scoccia E, Bellusci L, et al. The Pathophysiology of Pulmonary Embolism: A Clinical Review. J Clin Med. 2023 May 30;12(11):3799. doi: 10.3390/jcm12113799. PMID: 37298642; PMCID: PMC10254257.

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