Pulmonary Embolism: Symptoms, Risk Factors, and Emergency Treatment

Every year, tens of thousands of Americans die from pulmonary embolism, making it one of the most common preventable causes of hospital death. The CDC estimates that venous thromboembolism – the umbrella term that includes both deep vein thrombosis and pulmonary embolism – affects as many as 900,000 people in the United States each year and is linked to an estimated 60,000 to 100,000 deaths. A pulmonary embolism occurs when a blood clot – usually originating in the deep veins of the legs – breaks free and travels to the lungs, blocking blood flow. Despite its severity, many people have never heard of it until a diagnosis hits close to home. Recognizing the symptoms early and understanding who is most at risk can mean the difference between life and death. This guide covers what you need to know about PE – from the first warning signs to long-term recovery – and belongs alongside our broader medical conditions guide. It is educational only and is not a substitute for emergency care or advice from a qualified clinician.

What Is a Pulmonary Embolism?

A pulmonary embolism is a blockage in one or more arteries of the lungs. In most cases, the clot originates as a deep vein thrombosis (DVT) in the legs or pelvis and then travels through the bloodstream into the pulmonary vasculature. Once lodged in the lung arteries, the clot restricts blood flow, reduces oxygen levels, and places dangerous strain on the heart’s right side.

The severity of a PE depends on the size and number of clots, as well as the patient’s overall health. A small clot may cause only minor symptoms, while a large or “saddle” embolism – one that straddles the main pulmonary artery – can cause sudden cardiac arrest. The National Heart, Lung, and Blood Institute notes that for a substantial share of people, sudden death is the first and only sign of a PE, which underscores why prevention and early detection matter so much.

Not all pulmonary emboli come from leg clots. In rarer cases, fat from a broken bone, air bubbles, amniotic fluid during childbirth, or tumor fragments can cause the blockage. However, venous thromboembolism (VTE) – the umbrella term for DVT and PE – accounts for the vast majority of cases. Clinicians increasingly think of DVT and PE as two ends of the same disease process rather than separate conditions, which is why treating a leg clot promptly can prevent a life-threatening lung clot.

Symptoms and Warning Signs

The symptoms of pulmonary embolism can mimic many other conditions, which is one reason the diagnosis is frequently delayed. The most common symptom is sudden, unexplained shortness of breath. You may feel as though you cannot catch your breath even at rest, and the sensation typically worsens with exertion.

Sharp chest pain is another hallmark, often described as a stabbing sensation that gets worse when you breathe deeply, cough, or bend over. This pleuritic pain differs from the crushing pressure typically associated with a heart attack, though the two can be confused – and both are emergencies. If you are unsure whether chest symptoms are a clot, a heart problem, or something more benign, our explainers on what a heart attack feels like and telling anxiety from a heart attack may help, but when in doubt, call 911. A rapid or irregular heartbeat, coughing up blood (hemoptysis), lightheadedness, and excessive sweating are also common.

Some patients experience leg swelling, warmth, or tenderness before the PE occurs – signs of the underlying DVT. According to Mayo Clinic, about half of people with pulmonary embolism have no noticeable symptoms in their legs beforehand. This makes it critical to take respiratory symptoms seriously, especially if you have known risk factors.

When to seek emergency care: Call 911 or go to the nearest emergency room if you experience sudden shortness of breath, sharp chest pain, a rapid heartbeat, coughing up blood, or fainting. Pulmonary embolism can be fatal within hours without treatment, and there is no safe way to “rule it out” at home.

Risk Factors for Pulmonary Embolism

Understanding your risk profile is essential for prevention. The most significant risk factor is a history of deep vein thrombosis or a previous PE. Once you have had one venous clot, your lifetime risk of another increases substantially. Genetic clotting disorders – such as Factor V Leiden, the prothrombin gene mutation, or deficiencies in protein C, protein S, or antithrombin – raise the likelihood of clot formation and often run in families.

Prolonged immobility is another major contributor. Long-haul flights, extended bed rest after surgery, and sedentary stretches all slow blood flow in the deep veins, creating conditions favorable for clot formation. Major orthopedic surgeries – hip and knee replacements in particular – carry some of the highest PE risk among surgical procedures, which is why hospitals build clot prevention into recovery from these operations.

Hormonal factors also play a role. Estrogen-containing birth control pills and hormone replacement therapy increase clotting risk, as does pregnancy and the weeks immediately after delivery. Cancer and its treatments are strongly linked to PE; patients with active malignancies face a several-fold increased risk compared with the general population. Obesity, smoking, COVID-19 and other serious infections, prolonged hospitalization, and chronic conditions like heart failure and inflammatory bowel disease also contribute.

Age matters too. While PE can occur at any age, the risk rises significantly after 60. A combination of risk factors – say, an older adult recovering from hip surgery who also has a clotting disorder – can push the risk dramatically higher. Because risk stacks, it is worth telling any new clinician about your personal and family history of clots before surgery, hospitalization, or a long trip.

How Pulmonary Embolism Is Diagnosed

Diagnosing PE requires clinical suspicion backed by testing. Emergency clinicians often begin with a clinical probability score, such as the Wells criteria or the revised Geneva score, which assign points based on symptoms, heart rate, recent surgery, and other factors. Structured algorithms like the PERC rule (to safely avoid testing very-low-risk patients) and the YEARS algorithm are widely used to decide who needs imaging.

A D-dimer blood test can help rule out PE in lower-risk patients – if the D-dimer is normal, a clot is unlikely. However, D-dimer is elevated in many situations, including infection, recent surgery, pregnancy, and older age, so a raised result requires further investigation rather than confirming a clot on its own. Many centers now use an age-adjusted D-dimer threshold in older adults, which reduces unnecessary scans without missing significant clots.

The reference-standard imaging test for pulmonary embolism is CT pulmonary angiography (CTPA). This specialized CT scan uses contrast dye to visualize blood flow in the lung arteries and can detect clots with high accuracy. When CTPA is unavailable or contraindicated – for example, in patients with severe kidney disease, contrast allergy, or pregnancy where clinicians weigh radiation carefully – a ventilation-perfusion (V/Q) scan is an alternative. This nuclear-medicine test compares airflow and blood flow patterns in the lungs to identify mismatches suggestive of clots.

Additional tests often performed include echocardiography to assess strain on the right side of the heart, troponin and BNP levels to detect heart strain or muscle damage, and compression ultrasound of the legs to look for DVT. These extra tests do more than confirm the clot – they help the team judge how severe the PE is and how aggressively to treat it.

Emergency and Acute Treatment

Treatment for pulmonary embolism depends on its severity, and it is always directed by clinicians. The cornerstone of therapy is anticoagulation – blood thinners that prevent existing clots from growing and new clots from forming while the body gradually breaks down the clot that is already there. For most patients, treatment involves an injectable anticoagulant such as heparin or low-molecular-weight heparin and/or an oral anticoagulant. Direct oral anticoagulants (DOACs) such as apixaban and rivaroxaban have become first-line options for many patients because they require less routine monitoring and have fewer food interactions than warfarin. This article intentionally does not list doses: the right drug and amount depend on your kidney function, weight, bleeding risk, other medicines, and the cause of the clot, and only your prescriber can set them safely.

In high-risk (previously called “massive”) PE – a PE causing sustained low blood pressure or shock – clot-dissolving thrombolytic therapy may be necessary. Thrombolytics such as alteplase (tPA) dissolve clots rapidly but carry a significant risk of major bleeding, including bleeding in the brain, so they are reserved for life-threatening situations where the benefit outweighs that risk. The American Heart Association and other bodies recommend systemic thrombolysis when a PE is life-threatening and bleeding risk is acceptable.

For patients who cannot receive systemic thrombolytics, or who are deteriorating despite anticoagulation, catheter-based and surgical interventions may be considered. Catheter-directed therapy can deliver a lower dose of clot-busting drug directly to the blockage (catheter-directed thrombolysis) or physically remove or break up the clot (mechanical thrombectomy). These interventional approaches have grown quickly, and head-to-head research – including the PEERLESS trial reported in 2024-2025 – is actively comparing devices and strategies for intermediate- and high-risk PE; the best approach for a given patient is still an individualized, evolving decision. Surgical embolectomy – open-heart surgery to remove the clot – is reserved for the most critical cases. An inferior vena cava (IVC) filter may be placed to trap future clots before they reach the lungs when blood thinners cannot be used, though filters are generally considered a temporary measure rather than a long-term solution.

Submassive and Chronic Pulmonary Embolism

Between the extremes of small PE and high-risk PE lies intermediate-risk (formerly “submassive”) PE – a clot that causes right-heart strain without causing systemic low blood pressure. Managing intermediate-risk PE is one of the most debated topics in emergency and pulmonary medicine. Some patients improve with anticoagulation alone, while others deteriorate and need escalation to thrombolytics or catheter-based intervention. Multidisciplinary pulmonary embolism response teams (PERTs) have emerged at many hospitals to bring together emergency, pulmonary, cardiology, radiology, and surgical expertise and guide these complex decisions in real time.

A small percentage of patients develop chronic thromboembolic pulmonary hypertension (CTEPH) after a PE. In CTEPH, residual clot material organizes and scars in the pulmonary arteries, leading to persistently elevated lung pressures. Symptoms include progressive shortness of breath and exercise intolerance that persist for months after the acute event. Estimates suggest CTEPH affects a few percent of PE survivors. Pulmonary thromboendarterectomy (PTE) surgery is the definitive treatment, with excellent results in experienced centers. For patients who are not surgical candidates, balloon pulmonary angioplasty and medications such as riociguat may help. Because CTEPH is treatable but easy to miss, lingering breathlessness after a PE should always be reported to your clinician.

Prevention Strategies

Preventing a first or recurrent PE centers on reducing clot risk. After surgery, hospitals routinely use blood thinners and encourage early walking. Compression stockings and intermittent pneumatic compression devices help maintain blood flow during periods of immobility. If you are scheduled for major surgery, ask your care team about their VTE prophylaxis protocol – appropriate prophylaxis can substantially reduce the risk of postoperative clots.

For people with inherited clotting disorders or a history of recurrent VTE, long-term or even lifelong anticoagulation may be recommended. The decision involves balancing the risk of another clot against the risk of bleeding. Your hematologist or prescriber will consider factors such as the cause and severity of your clotting problem, your bleeding history, and your lifestyle – and this balance is reassessed over time, not decided once.

Lifestyle steps also matter. Staying physically active, maintaining a healthy weight, staying hydrated during travel, and avoiding prolonged immobility all reduce risk. During long flights or car rides, get up and walk every one to two hours, flex your calves while seated, and consider wearing compression socks. If you take estrogen-containing contraceptives and have additional risk factors, discuss alternative options with your provider. Understanding the healthcare costs of long-term anticoagulation therapy and monitoring can also help you plan ahead financially.

Recovery and Long-Term Outlook

Most patients with properly treated PE recover well, but the timeline varies. Anticoagulation therapy typically lasts at least three months for a first-time PE provoked by a temporary risk factor (like surgery). An unprovoked PE – one without an identifiable trigger – may warrant extended or indefinite treatment, as the recurrence risk is higher. The length of treatment is a clinician’s call and is periodically re-evaluated; it is not something to shorten on your own.

Post-PE syndrome is a recognized condition in which patients experience persistent shortness of breath, reduced exercise capacity, and fatigue for months or even years. A substantial share of PE survivors report some degree of functional limitation at one year, even without CTEPH. Cardiac and pulmonary rehabilitation and structured exercise programs have shown promise in improving outcomes for these patients.

Psychological effects should not be overlooked. Anxiety, depression, and post-traumatic stress symptoms are common after a life-threatening PE. Many patients report fear of recurrence, difficulty sleeping, and reluctance to travel. Addressing these concerns with your healthcare provider – and connecting with support groups – can significantly improve quality of life during recovery.

Frequently Asked Questions

Can a pulmonary embolism happen without DVT symptoms?

Yes. According to Mayo Clinic, roughly half of patients with PE have no noticeable leg symptoms. The clot may form in a deep vein and break free without causing obvious swelling or pain in the leg. This is why sudden shortness of breath or chest pain should always be evaluated promptly, even in the absence of leg complaints.

How long do you stay on blood thinners after a PE?

Treatment duration depends on the circumstances. A PE triggered by a known, temporary risk factor (such as surgery or a long flight) typically requires at least three months of anticoagulation. An unprovoked PE or one linked to an ongoing risk factor may require indefinite treatment. Your clinician weighs the recurrence risk against the bleeding risk to make a recommendation tailored to your situation – and you should never stop early on your own, because that can trigger another clot.

Is pulmonary embolism the same as a heart attack?

No. A heart attack occurs when blood flow to the heart muscle is blocked, usually by a plaque rupture in a coronary artery. A pulmonary embolism involves a clot blocking blood flow in the lung arteries. Both are medical emergencies with overlapping symptoms like chest pain and shortness of breath, but they have different causes and treatments. When you cannot tell them apart, treat it as an emergency and call 911.

Can you fly after having a pulmonary embolism?

Many clinicians advise waiting a few weeks after starting anticoagulation before flying, and some recommend waiting longer depending on the severity of the PE and how you are recovering. When you do fly, stay hydrated, move around the cabin regularly, wear compression stockings, and take your anticoagulant exactly as prescribed. Discuss specific travel plans with your healthcare provider before booking.

What is the survival rate for pulmonary embolism?

With prompt diagnosis and treatment, most people with PE survive. However, high-risk PE with cardiovascular collapse carries a much higher mortality rate even with aggressive treatment. Outcomes are strongly tied to how quickly the clot is recognized and treated, which is why early recognition and calling 911 matter so much. Exact survival figures vary by study and by how sick the patient is at diagnosis.

Do blood clots in the leg always turn into a PE?

No. Many DVTs are treated before any clot reaches the lungs, which is exactly why prompt treatment of leg clots matters. Signs of a possible DVT – swelling, pain, warmth, or redness in one leg or calf – deserve same-day medical evaluation. Treating a DVT early is one of the best ways to prevent a pulmonary embolism.

Living With and After Pulmonary Embolism

Surviving a pulmonary embolism is just the beginning of a longer journey. Work closely with your healthcare team to determine the right duration for anticoagulation, monitor for signs of CTEPH, and gradually return to physical activity. Many people find that a structured exercise program – even starting with simple walking – helps rebuild confidence and cardiovascular fitness.

Stay vigilant about new symptoms. If you develop worsening shortness of breath, leg swelling, or chest pain while on treatment, contact your provider immediately – and call 911 for the emergency signs listed at the top of this page. Keep all follow-up appointments, especially if you are taking warfarin, which requires regular INR monitoring. If you are on a DOAC, adherence is critical because these medications have short half-lives – missing doses can leave you unprotected, and doubling up to “catch up” can cause bleeding, so ask your prescriber what to do if you miss a dose.

Finally, become your own advocate. Know your risk factors, inform every new healthcare provider about your PE history, and do not hesitate to ask about preventive measures before surgery, hospitalization, or extended travel. Pulmonary embolism is serious, but with proper awareness and management, most people go on to live full, active lives.

This article is for general education and is not medical advice. It cannot diagnose a pulmonary embolism or replace emergency care. If you suspect a PE, call 911 immediately, and never start, stop, or change a blood thinner without your prescriber’s guidance.

Sources

• Centers for Disease Control and Prevention (CDC) – Venous Thromboembolism (Blood Clots): Data and Statistics; Diagnosis and Treatment
• National Heart, Lung, and Blood Institute (NHLBI) – Pulmonary Embolism
• Mayo Clinic – Pulmonary Embolism: Symptoms, Causes, Diagnosis & Treatment
• MedlinePlus (U.S. National Library of Medicine) – Pulmonary Embolus
• American Heart Association – Scientific statements on venous thromboembolism and pulmonary embolism management
• American College of Radiology – Appropriateness Criteria for suspected pulmonary embolism