Pulmonary embolism (PE) is a life-threatening medical condition that occurs when one or more arteries in the lungs become blocked by a blood clot. In many cases, these clots originate in the deep veins of the legs — a condition known as deep vein thrombosis (DVT) — before traveling to the lungs. A blood clot in the lung can reduce or completely cut off blood flow, making it extremely dangerous and potentially fatal if not treated promptly.
According to the Centers for Disease Control and Prevention (CDC), pulmonary embolism affects hundreds of thousands of people in the United States each year. What makes it particularly dangerous is that its symptoms can be subtle, vary widely from person to person, or even be mistaken for other conditions. Recognizing the warning signs early can be the difference between life and death.
In this article, we outline the 10 key symptoms of pulmonary embolism that you should never ignore, along with its main causes and prevention tips.
1. Sudden Shortness of Breath
One of the most hallmark symptoms of pulmonary embolism is a sudden and unexplained onset of shortness of breath. This occurs because when a blood clot blocks an artery in the lung, that portion of the lung can no longer participate in effective gas exchange, leading to a rapid drop in oxygen levels.
- The breathlessness often appears out of nowhere, even at rest or during minimal physical activity.
- It may worsen with exertion, such as climbing stairs or walking short distances.
- In severe cases, the person may feel like they are suffocating or cannot catch their breath at all.
- This symptom alone accounts for the majority of PE presentations and should always be evaluated urgently by a medical professional.
If you or someone you know experiences sudden, unexplained difficulty breathing — especially alongside other symptoms on this list — seek emergency medical care immediately.
2. Sharp Chest Pain
Chest pain associated with pulmonary embolism is typically sharp and stabbing in nature, and it is often described as pleuritic chest pain — meaning it worsens with deep breathing, coughing, or sneezing.
- The pain usually occurs on one side of the chest and may radiate to the shoulder, arm, jaw, or back.
- Unlike a typical heart attack, which is more often felt as pressure or squeezing, PE-related chest pain tends to be more localized and breathing-dependent.
- The pain results from irritation or inflammation of the pleura (the lining around the lungs) caused by the blocked blood supply.
- In massive PE cases, chest pain can be severe and central, mimicking a heart attack.
Any new or unexplained chest pain should be treated as a medical emergency until proven otherwise.
3. Rapid Heart Rate (Tachycardia)
When a blood clot obstructs the pulmonary arteries, the heart must work significantly harder to pump blood through the lungs. This increased cardiac workload often manifests as a rapid or irregular heartbeat, medically known as tachycardia.
- The heart rate may exceed 100 beats per minute, even without any physical exertion.
- Some patients describe it as a pounding, racing, or fluttering sensation in the chest.
- In severe cases, arrhythmias (irregular heart rhythms) can develop, which further complicates the clinical picture.
- A rapid heart rate combined with shortness of breath and chest pain is a classic triad of pulmonary embolism warning signs.
If you notice your heart beating unusually fast without a clear reason, consult a doctor promptly, especially if other PE symptoms are present.
4. Coughing Up Blood (Hemoptysis)
Coughing up blood or blood-streaked mucus — a condition known as hemoptysis — is one of the more alarming and serious symptoms associated with pulmonary embolism.
- This occurs when the lack of blood supply to lung tissue causes cell death (pulmonary infarction), leading to bleeding into the airways.
- The blood coughed up may appear bright red or rust-colored and is often mixed with phlegm or mucus.
- While not present in all PE cases, hemoptysis is strongly associated with pulmonary infarction — a more severe form of the condition.
- Even small amounts of blood in sputum are a red flag and require immediate medical evaluation.
Coughing up blood should never be dismissed or attributed to a minor illness. Always seek emergency medical attention immediately.
5. Dizziness, Lightheadedness, or Fainting
Reduced oxygen levels and compromised blood circulation resulting from a pulmonary embolism can deprive the brain of adequate oxygen, leading to symptoms such as dizziness, lightheadedness, or even fainting (syncope).
- Patients may feel unsteady, weak, or as though the room is spinning.
- Fainting episodes (syncope) are more common in massive pulmonary embolisms where blood flow is severely obstructed.
- In some individuals, this may be the very first noticeable symptom, making diagnosis challenging.
- Dizziness may also be accompanied by a sudden drop in blood pressure, contributing to the feeling of near-fainting.
Sudden fainting or persistent dizziness, particularly when combined with other symptoms like chest pain or shortness of breath, warrants urgent evaluation.
6. Low Blood Pressure (Hypotension)
In severe or massive pulmonary embolism cases, the blocked blood flow through the lungs can dramatically reduce the amount of blood returning to the left side of the heart. This results in a significant drop in blood pressure, a condition called hypotension.
- Blood pressure may drop suddenly and severely, sometimes to dangerously low levels.
- Symptoms include extreme weakness, cold and clammy skin, confusion, and shock-like states.
- This is considered a massive PE and represents the most life-threatening presentation of pulmonary embolism.
- Low blood pressure in the context of PE is associated with significantly higher mortality rates and requires immediate intensive medical intervention.
Sudden hypotension, especially when unexplained and accompanied by other PE symptoms, is a medical emergency that requires immediate hospitalization.
7. Swelling, Pain, or Redness in One Leg (DVT Symptoms)
As mentioned earlier, pulmonary embolism often originates from a deep vein thrombosis (DVT) — a blood clot that forms in the deep veins of the legs. Before the clot travels to the lungs, patients may experience symptoms in the affected leg.
- Swelling: One leg may become noticeably swollen compared to the other, often around the calf or thigh.
- Pain or tenderness: Patients may feel a dull ache, cramping, or soreness in the calf or along the inner thigh, especially when walking or standing.
- Warmth and redness: The skin over the clot may feel warm to the touch and appear reddish or discolored.
- Surface vein prominence: In some cases, superficial veins may become more visible or feel hard beneath the skin.
Not everyone with a DVT will develop a pulmonary embolism, but it is a major risk factor. If you notice unexplained swelling or pain in one leg, see a doctor promptly to rule out a blood clot.
8. Bluish Discoloration of the Skin (Cyanosis)
When the body’s oxygen levels fall dangerously low due to blocked blood flow in the lungs, the skin, lips, and fingertips may take on a bluish or grayish tint — a clinical sign known as cyanosis.
- Central cyanosis (around the lips and inside the mouth) indicates severely low blood oxygen levels and is a critical warning sign.
- Peripheral cyanosis (fingertips, toes, and extremities) may also occur due to poor circulation.
- Cyanosis in the context of PE signals that the body’s oxygen supply is critically compromised.
- This symptom typically accompanies other severe signs such as extreme shortness of breath and loss of consciousness.
Cyanosis is a medical emergency. If you observe this sign in yourself or someone else, call emergency services immediately.
9. Fever and Excessive Sweating
While fever is not among the most commonly highlighted symptoms of pulmonary embolism, it does occur in a significant number of patients. It is thought to result from the inflammatory response triggered by the presence of a blood clot in the lungs.
- The fever in PE is typically low-grade (below 38.5°C / 101.3°F), though higher temperatures can occur.
- It may be accompanied by night sweats or episodes of excessive perspiration.
- Because fever is associated with so many other conditions (infections, flu, etc.), it can delay the diagnosis of PE when present alone.
- When fever occurs alongside shortness of breath, chest pain, or a recent history of prolonged immobilization, PE should be considered and ruled out.
A low-grade fever that doesn’t respond to typical treatment and is accompanied by respiratory or cardiovascular symptoms should prompt medical evaluation for possible pulmonary embolism.
10. Anxiety and a Sense of Impending Doom
A lesser-known but clinically documented symptom of pulmonary embolism is an overwhelming sense of anxiety, restlessness, or what patients often describe as a “feeling of impending doom” — the inexplicable sensation that something is terribly wrong.
- This feeling is believed to be triggered by the body’s acute physiological distress response to severely reduced oxygen levels and compromised circulation.
- Patients may become extremely agitated, confused, or disoriented, particularly in cases of massive PE.
- Some individuals report a sudden onset of panic-like symptoms without a clear psychological trigger.
- Although anxiety can have many causes, when it arises abruptly alongside physical symptoms like shortness of breath, chest pain, or rapid heart rate, it may indicate a serious underlying condition such as PE.
Never dismiss a sudden and intense feeling of anxiety combined with physical symptoms — it can be your body’s way of signaling a potentially life-threatening emergency.
Main Causes of Pulmonary Embolism
Understanding what causes blood clots in the lungs can help identify people at risk. The most common causes and risk factors include:
- Deep Vein Thrombosis (DVT): The most frequent origin of pulmonary embolism. Blood clots in the deep veins of the legs or pelvis can break off and travel to the lungs.
- Prolonged immobility: Long periods of sitting still — such as during long-haul flights, car rides, or bed rest after surgery — slow blood circulation and promote clot formation.
- Surgery or trauma: Major surgeries (especially orthopedic procedures like hip or knee replacement) and physical injuries can activate the blood’s clotting mechanisms.
- Cancer: Certain cancers and cancer treatments increase the production of clotting factors in the blood, significantly raising PE risk.
- Inherited clotting disorders: Genetic conditions such as Factor V Leiden mutation, protein C or S deficiency, and antithrombin deficiency predispose individuals to abnormal clotting.
- Pregnancy and childbirth: Hormonal changes during pregnancy increase blood clotting tendency; the risk is further elevated during the postpartum period.
- Hormonal medications: Oral contraceptives and hormone replacement therapy (HRT) containing estrogen can increase clotting risk, especially in women who smoke or have other risk factors.
- Obesity: Excess body weight increases pressure on the veins of the legs and pelvis, promoting clot formation.
- Heart disease: Conditions such as heart failure or atrial fibrillation can lead to abnormal blood flow and increased clot formation risk.
- Age: The risk of PE increases with age, particularly in individuals over 60.
How to Prevent Pulmonary Embolism
While not all cases of pulmonary embolism can be prevented, there are several effective strategies to significantly reduce your risk:
- Stay active and avoid prolonged sitting: During long trips or periods of bed rest, make a point to get up and move regularly. If you must sit for long periods, flex and extend your ankles frequently to keep blood moving.
- Stay well hydrated: Drinking plenty of fluids — especially water — helps keep the blood from becoming too concentrated and prone to clotting.
- Wear compression stockings: Graduated compression stockings improve blood flow in the legs and are especially helpful for people at elevated risk of DVT.
- Maintain a healthy weight: Reducing excess body weight decreases pressure on the venous system in the legs and pelvis.
- Quit smoking: Smoking damages blood vessel walls and increases the tendency for clots to form.
- Know your family history: If you have a family history of blood clotting disorders, inform your doctor so that appropriate screening and precautions can be taken.
- Follow medical advice after surgery: If you have undergone major surgery, closely follow your healthcare provider’s post-operative care instructions, which may include blood thinning medications. Always consult your doctor before taking any medications.
- Manage underlying conditions: Effective control of heart disease, cancer, and other chronic conditions that raise PE risk is essential. Work closely with your healthcare team for personalized guidance.
Frequently Asked Questions (FAQ)
What is a pulmonary embolism?
A pulmonary embolism (PE) is a blockage in one or more of the pulmonary arteries in the lungs, most commonly caused by blood clots that travel from the deep veins of the legs or other parts of the body. It is a potentially life-threatening condition that requires prompt medical attention.
What are the first signs of a pulmonary embolism?
The earliest and most common signs include sudden shortness of breath, sharp chest pain (especially when breathing deeply), and a rapid heart rate. These symptoms can appear abruptly and without warning.
Can pulmonary embolism occur without symptoms?
Yes. In some cases — particularly with smaller clots — pulmonary embolism can be asymptomatic or present with very mild, nonspecific symptoms that are easily mistaken for other conditions. This is why PE is sometimes called a “silent killer.”
How serious is a blood clot in the lungs?
A blood clot in the lungs is a medical emergency. Without prompt treatment, pulmonary embolism can be fatal. It is one of the leading causes of cardiovascular death, second only to heart attack and stroke.
Who is most at risk of developing pulmonary embolism?
People at highest risk include those with a history of DVT, recent surgery or hospitalization, cancer patients, pregnant women, people with inherited clotting disorders, long-distance travelers, and individuals who are obese, elderly, or on estrogen-containing medications.
Can pulmonary embolism symptoms be confused with other conditions?
Yes. PE symptoms can closely mimic those of a heart attack, pneumonia, asthma, anxiety disorders, or even musculoskeletal pain. This is why a proper clinical evaluation — including imaging studies and blood tests — is critical for an accurate diagnosis.
What should I do if I suspect a pulmonary embolism?
If you or someone else experiences sudden shortness of breath, chest pain, rapid heart rate, or any combination of the symptoms described in this article, call emergency services (911 or your local emergency number) immediately. Do not wait to see if symptoms improve on their own.
References:
- Mayo Clinic – Pulmonary Embolism: Symptoms and Causes
- Centers for Disease Control and Prevention (CDC) – Venous Thromboembolism Data & Statistics
- National Heart, Lung, and Blood Institute (NHLBI) – Pulmonary Embolism
- Johns Hopkins Medicine – Pulmonary Embolism
- Healthline – Pulmonary Embolism: Symptoms, Causes, and Diagnosis