Understanding Pulmonary Embolism: Symptoms, Causes, and Prevention

Pulmonary embolism symptoms can vary widely. The most common signs include sudden shortness of breath, sharp chest pain that worsens when breathing deeply or coughing, and a persistent cough that may produce bloody mucus. Some people also experience rapid heartbeat or lightheadedness. These symptoms can come on quickly and may feel similar to a heart attack. However, about half of people with a pulmonary embolism have no noticeable symptoms at all, which can make early diagnosis difficult.

Depending on the size of the clot and a person’s overall health, other signs may appear. These include clammy or bluish skin, fever, dizziness, or an irregular heartbeat. Swelling or pain in one leg—especially the calf—could point to deep vein thrombosis, a common source of the clot that triggers a pulmonary embolism. Any combination of these symptoms, especially if they occur suddenly, should be treated as a medical emergency.

Most pulmonary embolisms happen when a blood clot forms in the legs (a condition called deep vein thrombosis) and breaks loose, traveling to the lungs. The clot blocks blood flow in a lung artery, reducing oxygen and potentially damaging lung tissue. Though less common, other substances—like fat from a broken bone, air bubbles, or tumor fragments—can also cause blockages. If the clot cuts off blood flow long enough to damage lung tissue, it’s known as a pulmonary infarction.

Certain health issues increase the likelihood of developing blood clots. Heart disease, specific cancers, and some cancer treatments—like chemotherapy—raise clotting risk. Major surgeries, especially joint replacements or abdominal procedures, are another key factor. People with a family history of clots or clotting disorders also face a higher chance of pulmonary embolism, even without other clear triggers.

Beyond medical conditions, lifestyle and hormonal factors can raise the risk of pulmonary embolism. Long periods of inactivity—such as being on bed rest or sitting for hours during travel—make it easier for clots to form. Smoking, obesity, and pregnancy also increase risk, as do hormonal birth control and estrogen therapy. These factors can affect blood flow or clotting tendencies, especially when combined.

Pulmonary embolism isn’t always easy to identify, especially when symptoms are mild or overlap with other conditions. To confirm a diagnosis, doctors may order a CT scan, MRI, or pulmonary angiogram to check for blockages in the lungs. An ultrasound of the legs can help detect deep vein clots. Blood tests may also be used to check oxygen levels and markers that indicate abnormal clotting.

Pulmonary embolism usually requires immediate medical care. Most patients are given blood thinners (anticoagulants) to stop new clots from forming and keep existing ones from getting bigger. In emergencies, clot-busting drugs (thrombolytics) may be used to quickly dissolve the blockage, though these carry higher risks of bleeding. Blood tests help guide treatment and monitor safety.

Some patients may need additional measures. Compression stockings are often recommended to reduce the risk of deep vein thrombosis, especially after surgery or prolonged inactivity. In severe or recurring cases, doctors might surgically remove the clot or insert a filter in a large vein to stop new clots from reaching the lungs. These interventions don’t prevent clots from forming, but they help reduce serious complications.

If not treated quickly, a pulmonary embolism can be fatal — about one-third of undiagnosed or untreated cases result in death. With fast, effective treatment, the survival rate improves dramatically. One potential long-term complication is pulmonary hypertension, where high pressure builds up in the lung arteries. This strains the heart and can lead to lasting damage over time.

Preventing blood clots is the best way to avoid a pulmonary embolism. Hospitals often use blood thinners, leg elevation, and compression stockings to protect at-risk patients during recovery. For people on long flights or car trips, it helps to stay hydrated, move around regularly, and avoid sitting still for long periods. Those with known risk factors may also benefit from lifestyle changes or medications to lower their chances of clotting.