Pulmonary embolism is a serious medical emergency that occurs when a blood clot blocks an artery in the lungs, cutting off vital blood flow and oxygen supply. This sudden blockage can damage the lungs, strain the heart, and without quick treatment, may even be life-threatening. Understanding the warning signs and knowing when to seek immediate help can make all the difference in outcomes.

Understanding How Common Pulmonary Embolism Is

Pulmonary embolism ranks as one of the most common heart and blood vessel diseases worldwide. It stands third in line behind only heart attack and stroke, making it a significant health concern that affects hundreds of thousands of people each year.^[2] In the United States alone, approximately 900,000 people experience a pulmonary embolism annually, which translates to a substantial number of individuals facing this potentially deadly condition.^[2]

The statistics surrounding pulmonary embolism reveal its serious nature. About 33 percent of people with a pulmonary embolism die before receiving a diagnosis and appropriate treatment, highlighting the critical importance of recognizing symptoms early and seeking immediate medical attention.^[2] In Europe, the condition affects roughly 430,000 people per year, with deaths ranging from 30,000 to 40,000 annually.^[4]

Despite these concerning numbers, there is reason for hope. When pulmonary embolism is caught quickly and treated promptly, it is seldom fatal. With timely diagnosis and proper medical intervention, the chance of death decreases dramatically, transforming what could be a fatal condition into one that many people survive and recover from.^[2]

What Causes a Blood Clot to Travel to the Lungs

The journey of a pulmonary embolism typically begins far from the lungs themselves. In most cases, the condition starts when a blood clot forms in a deep vein, usually in the leg. This condition is known as deep vein thrombosis, or DVT for short. When part of this clot breaks free, it travels through the bloodstream, moving up through the right side of the heart before finally reaching the lungs where it becomes stuck in an artery.^[1]

The blockage happens because the clot acts like a cork in a bottle, preventing blood from flowing properly through the lung’s arteries. Since blood carries oxygen throughout the body, this blockage means less oxygen reaches the lungs and, consequently, the rest of the body. At the same time, the heart has to work much harder to push blood through, which increases pressure in the pulmonary arteries (the blood vessels that carry blood from the heart to the lungs).^[2]

While blood clots from the legs account for the vast majority of pulmonary embolisms, the condition can rarely be caused by other materials entering the bloodstream. In uncommon circumstances, air bubbles, clumps of fat from broken bones, or even parts of a tumor can travel to the lungs and create a blockage, though these situations are far less frequent than blood clots.^[4]

Several specific situations can lead to blood pooling and clot formation. After surgery, especially operations on the pelvis, hip, knee, or leg, blood flow naturally slows down during recovery, increasing the likelihood of clot formation. Long periods of bed rest following illness or injury create similar conditions where blood moves more sluggishly through the veins. Even extended periods of sitting, such as during long airplane flights, train journeys, or car trips lasting more than three or four hours, can allow blood to collect in the lower legs, potentially forming clots.^[2]

Who Is Most at Risk for Developing Pulmonary Embolism

While anyone can develop a pulmonary embolism, certain groups of people face higher odds of experiencing this condition. Age plays a significant role, with risk increasing as people get older, particularly after reaching age 40. The body’s natural clotting mechanisms can become less balanced with age, making older adults more susceptible to developing dangerous blood clots.^[5]

People with cancer face elevated risk for several reasons. Some types of cancer increase the blood’s tendency to clot, and chemotherapy treatments can further heighten this risk. Similarly, individuals with heart conditions including congestive heart failure, atrial fibrillation, heart attack, or stroke are more vulnerable to developing blood clots that could lead to pulmonary embolism.^[2]

Pregnancy and the period immediately following childbirth create changes in the body that increase clotting risk. The risk remains highest for approximately six weeks after giving birth. Women taking hormone-based medications, whether birth control pills or hormone replacement therapy, also face increased risk because these medications can affect the blood’s clotting factors.^[5]

Obesity adds strain to the circulatory system and can slow blood flow, particularly in the legs, making it easier for clots to form. Smoking damages blood vessels and affects how blood flows and clots, putting smokers at higher risk. People who have experienced major trauma or bone fractures, particularly in the legs or hips, face increased risk because injury to blood vessels can trigger clot formation.^[5]

Certain genetic conditions that affect blood clotting run in families. People who inherit these conditions have blood that clots more easily than normal, placing them at lifelong risk for developing blood clots. Anyone with a family history of blood clots should discuss this with their doctor, as genetic testing may reveal whether they carry these inherited risk factors.^[5]

Recognizing the Warning Signs

The symptoms of pulmonary embolism can appear suddenly, developing within seconds or minutes, or they may emerge gradually over days or weeks. Some people experience only mild symptoms initially that progressively worsen, while others may have no symptoms at all until serious complications develop. This variability makes it especially important to pay attention to any unusual changes in how you feel.^[2]

Shortness of breath stands out as one of the most common and noticeable symptoms. This breathlessness often appears suddenly and catches people off guard. It may occur even when resting and typically gets worse with any physical activity. Unlike the temporary breathlessness from exertion that improves with rest, the shortness of breath from pulmonary embolism does not go away and may continue to worsen.^[1]

Chest pain represents another key warning sign. The pain is often sharp and may feel similar to a heart attack, which is why many people initially think they are having cardiac problems. This chest pain characteristically worsens when taking a deep breath or coughing. The discomfort can be so intense that it prevents people from being able to breathe deeply, and it may spread to the arm, back, shoulder, neck, or jaw.^[1]

Rapid breathing and a fast heartbeat often accompany pulmonary embolism as the body tries to compensate for reduced oxygen levels. Some people develop a cough, which may or may not produce bloody mucus. The skin can take on an unhealthy appearance, becoming pale, clammy, or even bluish in color due to insufficient oxygen. Excessive sweating may occur, and some individuals experience feelings of anxiety, lightheadedness, or faintness. In severe cases, people may pass out completely.^[2]

You might also notice signs in your legs that suggest a deep vein thrombosis is present or forming. These include swelling, redness, warmth, pain, or tenderness, particularly in one leg. The presence of leg symptoms alongside breathing problems should raise immediate concern for pulmonary embolism.^[7]

Steps You Can Take to Lower Your Risk

Prevention plays a crucial role in avoiding pulmonary embolism, especially for people who know they have risk factors. One of the most effective prevention strategies is simply staying active. Movement keeps blood flowing properly through the veins, particularly in the legs where clots most commonly form. After surgery or during illness, getting up and moving as soon as doctors say it is safe can significantly reduce clot risk.^[4]

For people who must sit for extended periods, whether for work or during long-distance travel, simple leg exercises can help maintain blood flow. Pumping your feet up and down by pulling your toes toward your knees then pointing them down again helps activate the calf muscles, which act like pumps to push blood back up toward the heart. Flexing your feet every hour when confined to bed during illness or recovery serves the same protective purpose.^[17]

During long trips by car, plane, train, or bus, taking regular breaks to walk around becomes important. On car journeys, stopping every hour to stretch and walk helps prevent blood from pooling in the legs. On airplanes or trains, getting out of your seat and walking up and down the aisle every hour, when possible, provides similar benefits. Wearing loose, comfortable clothing during travel also helps maintain good circulation.^[21]

Some doctors recommend wearing compression stockings, which are special tight-fitting socks that help blood flow more easily through leg veins. These stockings are tighter at the ankle and gradually become less tight moving up the leg, which helps push blood upward. However, compression stockings should only be worn if a healthcare professional prescribes them, as they are not appropriate for everyone and improper use can cause problems.^[17]

Maintaining a healthy lifestyle provides broad protection against blood clots. This includes staying physically active on a regular basis, maintaining a healthy body weight, and quitting smoking if you currently smoke. Smoking damages blood vessels and affects how blood clots, so stopping this habit removes a significant risk factor. Drinking plenty of water helps prevent dehydration, which can make blood thicker and more likely to clot.^[7]

Women who are taking hormone-based birth control or hormone replacement therapy should discuss their individual risk factors with their doctor. These medications increase clotting risk, and for some women with other risk factors, alternative options may be safer. Pregnancy also increases clotting risk, so pregnant women and those who have recently given birth should be particularly attentive to prevention strategies and warning signs.^[5]

Getting vaccinated against COVID-19, influenza, and pneumonia serves as another prevention measure. Serious infections from these illnesses can increase the risk of blood clots, so vaccination provides indirect protection by preventing severe illness.^[17]

How the Body Changes When Pulmonary Embolism Occurs

When a blood clot lodges in a lung artery, it sets off a cascade of changes in how the body functions. The most immediate problem is that the blockage prevents blood from flowing to part of the lung. Since blood carries oxygen to tissues, the blocked area cannot pick up oxygen from the air you breathe. This means less oxygen becomes available for the entire body, affecting all organs and tissues that depend on oxygen-rich blood to function properly.^[2]

The heart faces increased strain when trying to push blood through the partially blocked lung arteries. Normally, the right side of the heart pumps blood through the lungs with relatively little resistance. When a clot blocks an artery, the heart must work much harder to move blood past the obstruction. This extra workload increases blood pressure in the pulmonary arteries, a condition called pulmonary hypertension.^[5]

Over time, if the blockage is large or if multiple clots are present, the right side of the heart can become overstrained and begin to fail. This is known as right ventricular failure and represents one of the most serious complications of pulmonary embolism. When the heart cannot pump effectively, blood backs up in the veins, and organs throughout the body receive insufficient blood supply.^[2]

The lung tissue beyond the blockage can suffer damage from lack of blood flow. In some cases, lung tissue may die if blood flow is completely cut off for too long. Even after the clot is treated and blood flow is restored, some lung damage may be permanent, potentially affecting breathing capacity in the long term.^[2]

The body attempts to compensate for reduced oxygen levels by breathing faster and increasing heart rate. These are the automatic responses you experience as rapid breathing and rapid heartbeat. However, these compensatory mechanisms can only do so much, and without medical treatment to remove or dissolve the clot, the body’s systems continue to struggle under the strain of inadequate oxygen delivery.^[6]