Pulmonary Embolism: Symptoms, Warning Signs, and Emergency Actions

A pulmonary embolism is a sudden lung artery blockage, usually by a blood clot from the legs. It prevents oxygen from reaching your lungs and can strain your heart. PE affects up to 900,000 Americans yearly, with many cases being fatal without quick treatment. Emergency symptoms include sharp chest pain, trouble breathing, coughing blood, or fainting. Never ignore these signs — call emergency services immediately.

In plain words

A pulmonary embolism (PE) is a sudden blockage in a lung artery. It happens when a blood clot from another part of the body, usually the legs, travels to the lungs. This blockage stops oxygen from getting to your lungs and can put strain on your heart. PE is a serious condition that needs quick treatment. About 900,000 people in the U.S. get PE each year, and it can be deadly without fast care. Emergency signs include sudden chest pain, trouble breathing, coughing up blood, or fainting. If you have these symptoms, call emergency services right away.

What is Pulmonary Embolism: Symptoms, Warning Signs, and Emergency Actions?

Symptoms

Early symptoms

Sudden shortness of breath: Feeling like you can't get enough air, even when resting. This often develops abruptly and may worsen over hours. (3) (5)
Sharp chest pain: Stabbing or pleuritic chest pain that worsens when breathing deeply, coughing, or bending. May feel like a heart attack. (3) (2)
Cough with blood: Coughing up blood-streaked sputum (hemoptysis). The blood may be bright red or look like coffee grounds. (3)
Leg pain or swelling: Usually in one calf, often with redness or warmth. This suggests deep vein thrombosis (DVT), the clot source before it travels to lungs. (2) (1)
Rapid heartbeat: Heart may beat faster than 100 bpm as your body tries to get oxygen despite the lung blockage. (5)
Mild fever or sweating: Some people develop a low-grade fever or break out in cold sweats as the body reacts to the clot. (3)

Serious or emergency symptoms

Crushing chest pressure: Severe central chest pain that feels like being squeezed, similar to a heart attack. The clot is putting extreme strain on your heart. Call emergency services immediately — this suggests a massive PE. (5) (6)
Fainting or loss of consciousness: Sudden syncope (passing out) means your brain isn't getting enough oxygen. This is life-threatening. Call emergency services immediately. Do not try to drive yourself. (2) (6)
Blue lips or nails (cyanosis): Skin turning blue from lack of oxygen is a late, critical sign of respiratory failure. Call emergency services immediately — you need oxygen therapy fast. (5) (6)
Extremely low blood pressure: Symptoms like dizziness, confusion, or feeling faint when standing may indicate cardiogenic shock from a massive PE. Call emergency services immediately — this has high mortality without rapid hospital care. (6)

Causes

Primary causes

Blood clots from deep veins (DVT): Most PEs start as clots in deep leg veins that break loose and travel to lungs. These venous thromboembolisms (VTEs) are the primary cause. (1) (2)
Other rare clot sources: Less commonly, clots form in pelvic, arm, or heart veins. Fat droplets (after bone fractures) or air bubbles can also block lung arteries but are rare. (5)
Risk factor combinations: Pulmonary embolism usually occurs when multiple risk factors combine — like surgery plus genetic clotting tendency. Rarely happens without identifiable risks. (1) (7)

Risk factors

Prolonged immobility

Sitting still for over 4 hours (long flights, bedrest) lets blood pool and clot. Post-surgery immobilization is particularly risky. (1) (7)

Recent surgery or trauma

Especially hip/knee replacements, abdominal/pelvic surgeries, or leg fractures. Bodily injury activates clotting mechanisms. (1)

Cancer and chemotherapy

Some tumors promote clotting. Treatments further increase risk. Approximately 20% of cancer patients develop VTE. (7)

Estrogen medications

Birth control pills, patches, and hormone therapy raise clotting risks, especially if coupled with smoking. (1)

Genetic clotting disorders

Conditions like Factor V Leiden or Protein C deficiency create lifelong higher VTE risks. (1)

Diagnosis

Doctors use a combination of tests for PE: 1) Blood tests (D-dimer) check for clot breakdown products. 2) Imaging like CT pulmonary angiography shows lung arteries. 3) Ultrasound finds leg DVTs. 4) ECG and oxygen levels assess heart strain. The AHA stresses that clinical probability scores (like Wells Criteria) guide testing decisions, as no single test is perfect.

CT pulmonary angiography (CTPA)

Gold standard imaging—injected dye highlights lung arteries to locate blockages. Quick and widely available in ERs. (6)

D-dimer blood test

Measures clot breakdown products. A negative result helps rule out PE in low-risk cases. (6)

Ventilation-perfusion (VQ) scan

Nuclear imaging that compares air flow (ventilation) to blood flow (perfusion) in lungs. Used when CT is unavailable. (6)

Leg ultrasound

Finds deep vein clots that could become PEs. Often done when imaging is inconclusive. (6)

Treatment

Medication options

Anticoagulants (blood thinners)

Prevents new clots from forming and stops existing clots from growing. Given first as injections (heparin/enoxaparin), then transitioned to pills. (4) (5) (6)

Thrombolytics (clot busters)

Dissolves existing clots in severe PE cases with heart strain or shock. Works faster than anticoagulants but carries higher bleeding risks. (6)

Vena cava filter

A metal device placed in the body's main vein (vena cava) to catch clots before they reach lungs. Used when anticoagulants are unsafe. (6)

Lifestyle and self-care

Early mobility after surgery: Walking as soon as medically safe prevents blood pooling. Even ankle exercises in bed help circulation during recovery. (1)
Compression stockings: Medical-grade calf compression helps blood flow if you're immobile or have prior clots. Must be properly fitted. (1)
Stay hydrated and move regularly: During travel or desk work, drink water and walk/stretch every 1-2 hours. Dehydration thickens blood. (1)
Smoking cessation: Quitting improves vascular health and removes a major clotting risk factor, especially with estrogen use. (1)

Always discuss dosing and treatment changes with your own prescriber.

Possible complications

Chronic thromboembolic pulmonary hypertension (CTEPH): Rare but serious — multiple PE episodes scar lung arteries, raising blood pressure in lungs and straining the heart over years. (7)
Recurrent pulmonary embolism: About 33% of PE survivors have another episode within 10 years if not on long-term anticoagulation or if risks persist. (7)
Post-PE syndrome: Persistent shortness of breath and exercise intolerance even after clots dissolve, affecting up to 50% of survivors. (7)
Bleeding from anticoagulants: The main treatment risk — ranging from easy bruising to life-threatening hemorrhages. Requires careful dosing and monitoring. (6)

When to see a doctor

Routine follow-up

Discuss PE prevention if you have multiple risk factors (e.g., upcoming surgery plus family clot history). Your doctor may recommend temporary anticoagulants or compression stockings. (1)
After PE treatment, keep all follow-up appointments to adjust medications and check for complications like post-PE syndrome. (4)

Seek emergency care

Call emergency services immediately for sudden breathing difficulty with chest pain, coughing blood, or fainting. PE symptoms can worsen rapidly. (2) (5)
Seek emergency care if on blood thinners and experience: severe headache/uncontrolled bleeding/fall injuries — these suggest dangerous bleeding complications. (4)

Frequently asked questions

Is pulmonary embolism an emergency?

Yes. Up to 25% of pulmonary embolisms cause sudden death before diagnosis. Even non-fatal PEs can damage lungs and strain the heart. NHS and CDC guidelines stress that sudden breathing difficulty with chest pain requires immediate 911 response — never 'wait and see' with PE symptoms. (2) (1)

What are the warning signs of pulmonary embolism?

Key red flags include: 1) Sudden breathlessness (even at rest), 2) Sharp chest pain worse when breathing, 3) Coughing up blood, 4) Fainting or feeling faint. NHS reports that 85% of PE patients have sudden breathing trouble, and 50% have chest pain. Leg swelling (often in one calf) is another clue pointing to DVT as the clot source. (3) (5)

What should I do if pulmonary embolism happens?

1) Call emergency services immediately — never drive yourself. 2) Sit still to avoid dislodging more clots. 3) Chew an aspirin if available (may help while waiting). 4) Note symptom onset time — this guides hospital treatment decisions. The CDC emphasizes that every minute matters with PE; treatment delays increase complications. (2) (1)

How quickly do I need help for pulmonary embolism?

Immediately. Studies show PE mortality rises 30% per hour without treatment. The NHS and AHA consider PE a 'time-critical' diagnosis where delays directly harm outcomes. With massive PE, half of deaths occur within 1 hour. Even milder PEs can progress rapidly — early treatment prevents long-term lung damage. (6) (2)

What happens at the hospital for pulmonary embolism?

You'll get: 1) Emergency imaging (usually CT scan) to confirm PE. 2) Oxygen if levels are low. 3) IV blood thinners like heparin. 4) Possible clot-busting drugs if unstable. MedlinePlus notes most patients stay 5-7 days to stabilize, then continue oral anticoagulants for 3+ months. Severe cases may need ICU care or surgery. (4) (5) (6)

References

CDC — Venous Thromboembolism (Blood Clots) source 1
NHS — Pulmonary embolism source 2
NHS — Pulmonary embolism - Symptoms source 3
NHS — Pulmonary embolism - Treatment source 4
MedlinePlus — Pulmonary embolism source 5
AHA — Management of Massive and Submassive Pulmonary Embolism source 6
WHO — Venous thromboembolism (VTE) source 7