How long will I need to be on blood thinners after a pulmonary embolism?

Usually at least three months, and often longer. A PE triggered by a temporary event such as surgery may need a shorter course, while an unprovoked PE or one linked to ongoing risk such as cancer often calls for extended or indefinite treatment. The duration balances clotting risk against bleeding risk.

Why did I get a pulmonary embolism when I am otherwise healthy?

Between a third and a half of pulmonary embolisms happen with no obvious trigger. Sometimes there is a subtle contributor found later, such as an inherited clotting tendency, and sometimes there is no clear reason. An unprovoked PE is real and worth treating fully.

I still feel short of breath months after my PE. Is that normal?

Lingering breathlessness in the year after a PE is common and often part of post-PE syndrome, which improves with a gradual return to activity. Persistent shortness of breath should still be checked, because a small number of people develop chronic thromboembolic pulmonary hypertension (CTEPH), a treatable condition where old clots keep lung pressures high.

Pulmonary Embolism: A Cardiologist's Guide to a Blood Clot in the Lungs

Dr. Damian Rasch, D.O.

Medically Reviewed & Edited

Board-Certified Invasive Cardiologist
Encinitas and La Jolla, CA

Developed with digital research and writing assistance, then medically reviewed and edited by Dr. Rasch to ensure clinical accuracy and adherence to current evidence-based guidelines.

Last reviewed and updated on July 11, 2026

Quick Facts:

What it is: A pulmonary embolism (PE) is a blood clot that lodges in the arteries of the lungs. Most of the time the clot forms in a deep vein of the leg or pelvis, breaks loose, and travels up through the heart into the lungs.
How it feels: The most common symptoms are sudden shortness of breath, sharp chest pain that's worse with a deep breath, a fast heartbeat, and low oxygen. Some people cough up a little blood. The symptoms are easy to mistake for other things, which is why testing is so important.
Who's at risk: Recent surgery, a long period of immobility, major injury, active cancer, pregnancy and the weeks after delivery, estrogen-containing birth control, obesity, older age, and inherited clotting tendencies. About a third to a half happen with no obvious trigger.
How it's treated: Blood thinners are the foundation, and most people are treated with a once- or twice-daily pill. Large, dangerous clots may need clot-busting drugs or a catheter procedure.
The outlook: Most people who are diagnosed and treated promptly recover well. The danger is a clot large enough to strain the heart, which is why a sudden, severe presentation is an emergency. Call 911.

A pulmonary embolism is one of those diagnoses that can range from "we caught it early, here's your prescription, you'll be fine" to a true life-threatening emergency, sometimes in the same afternoon. It's common, it's treatable, and it's also one of the more commonly missed serious diagnoses, because the symptoms overlap with so many ordinary things. This is the explanation I give patients and families who want to understand what a pulmonary embolism is, how we find it, how we treat it, and what recovery actually looks like.

What a pulmonary embolism is

Your lungs are where blood picks up oxygen. Blood flows from the right side of your heart into the pulmonary arteries, the vessels that carry it into the lungs, and returns freshly oxygenated. A pulmonary embolism is a blockage in one of those pulmonary arteries, almost always caused by a blood clot.

Here's the part that surprises people. The clot usually doesn't form in the lung at all. It forms in a deep vein, most often in the leg or pelvis, a problem we call a deep vein thrombosis, or DVT. A piece of that clot breaks loose, rides the bloodstream up through the right side of the heart, and gets stuck in the lungs where the arteries branch into smaller and smaller vessels. The DVT and the PE are really two ends of the same disease, which is why doctors group them together under the term venous thromboembolism.

This is not a rare event. Pulmonary embolism affects somewhere between 60 and 120 people per 100,000 each year, and it's linked to roughly 60,000 to 100,000 deaths a year in the United States. Those numbers are part of why we take even a suspicion of PE seriously and test for it rather than waiting to see what happens.

What it feels like, and why it's easy to miss

The classic pulmonary embolism comes on suddenly. The most common symptom, in about 80 percent of people, is shortness of breath that appears out of nowhere. Around 60 to 70 percent have chest pain that's sharp and gets worse when they breathe in deeply, cough, or move, a pattern doctors call pleuritic pain. Most have a fast heart rate, and about 70 percent have a lower-than-normal oxygen level when we check it.

Some people cough up a small amount of blood, which happens in roughly 5 to 13 percent of cases. A smaller group, about 10 to 20 percent, arrives in serious trouble with a dangerously low blood pressure, fainting, or shock. That's the presentation that needs emergency treatment within minutes rather than hours.

The reason a PE gets missed is that none of these symptoms belong only to a pulmonary embolism. Sudden breathlessness and chest pain describe a heart attack, a panic attack, pneumonia, a flare of asthma, and a dozen other things. About 40 percent of people with a confirmed PE also have a clot in a deep leg vein, but only half of them have any leg swelling or pain to hint at it. Because the signs are so nonspecific, we can't reliably diagnose or rule out a PE by exam alone. Objective testing is the only dependable way to know, and that's not a failing of the doctor, it's the nature of the disease.

Who is at risk

Blood clots form when something tips the balance toward clotting, and pulmonary embolism usually comes from a mix of a person's background risk and a specific trigger. The strongest short-term triggers are major surgery, a long stretch of immobility, and serious injury or trauma. Together these account for about a fifth of all cases. Anything that keeps blood sitting still in the legs, whether that's a hospital stay, a cast, or a very long flight or car ride, raises the risk.

Among the risk factors that stick around, active cancer is the single most common, also responsible for roughly a fifth of cases. Cancer makes the blood more prone to clotting, and some treatments add to that. Other important contributors include older age, estrogen-containing birth control, pregnancy and the postpartum weeks, obesity, and inherited conditions that make the blood clot too easily, which doctors call thrombophilias.

One point I want patients to hear clearly. Somewhere between a third and a half of pulmonary embolisms are what we call unprovoked, meaning they happen with no identifiable trigger at all. So the absence of an obvious cause does not make a PE less real or less dangerous. It sometimes just means we look a little harder afterward for an underlying reason.

How we diagnose it

Because the symptoms are nonspecific, we use a stepwise approach that the 2026 national guidelines lay out clearly. It's designed to confirm a PE quickly in the people who have one while sparing everyone else an unnecessary scan.

The first step is estimating how likely a PE is before any imaging, using a scoring tool such as the Wells or Geneva score, or experienced clinical judgment. That probability decides what comes next. For people at low or moderate probability, the next step is a blood test called a D-dimer, which measures a breakdown product of blood clots. A normal D-dimer in someone who wasn't high-risk to begin with is very reassuring and can rule a PE out without a scan. We use a higher threshold in patients over 50, since D-dimer naturally rises with age. And for people at very low probability, a simple checklist called the PERC rule can safely close the door on PE without even drawing the D-dimer.

When the probability is high, or the D-dimer is up, we move to imaging. The test of choice is a CT pulmonary angiogram, or CTPA, a CT scan with contrast dye that lights up the pulmonary arteries and shows a clot directly. It's accurate, finding about 94 percent of PEs, and it's fast. When the dye can't be used, for example in someone with a contrast allergy or poor kidney function, a ventilation-perfusion scan, known as a V/Q scan, is a good alternative that looks at airflow and blood flow through the lungs instead.

How we treat it

The foundation of treatment is anticoagulation, which means blood thinners. Blood thinners don't dissolve the clot that's already there. They stop it from growing and stop new clots from forming, and your body's own systems gradually break down the existing clot over the following weeks. For most people, that's enough.

The preferred blood thinners today are the direct oral anticoagulants, or DOACs, a group that includes apixaban (Eliquis), rivaroxaban, edoxaban, and dabigatran. We reach for these over the older drug warfarin because they work just as well, cause less serious bleeding, including a lower risk of bleeding into the brain, and are far more convenient since they don't require the routine blood monitoring warfarin needs. When someone needs a fast-acting injectable blood thinner first, we generally use low-molecular-weight heparin, which causes fewer recurrent clots and fewer platelet problems than the older unfractionated heparin.

Not every PE is treated the same way, and the 2026 guidelines introduced a system that sorts patients into categories based on how much the clot is straining the heart. That's the key question. A small clot in a stable patient is a very different situation from a large clot that's overwhelming the right side of the heart.

For patients whose blood pressure has dropped dangerously low, generally a top number under 90, we consider clot-busting drugs given through the vein, called systemic thrombolysis. These powerful medications dissolve the clot quickly and lower the risk of death in this high-risk group. The trade-off is real, though. Thrombolysis reduces 30-day death rates by a bit under 2 percent in absolute terms, from about 3.9 to 2.3 percent, but it raises the risk of a serious or brain hemorrhage by roughly 1.4 percent, so we reserve it for people sick enough to need it. For patients in between, or those who can't safely receive full-dose clot busters, we have catheter-based options that deliver clot-dissolving drugs right at the clot or physically remove it, along with surgery and heart-lung support machines in the most severe cases. Many hospitals now assemble a pulmonary embolism response team, or PERT, that brings several specialists together quickly to choose the best approach for a complicated case.

How serious it is

The honest answer is that it depends almost entirely on how much strain the clot puts on your heart, and we have good tools to measure that. For low-risk patients, identified with a score called the sPESI, the risk of dying within 30 days is under 1 percent. For higher-risk patients, it climbs to about 5 to 10 percent. For those who arrive with a dangerously low blood pressure, the 30-day risk is around 20 percent, which is why that presentation is a true emergency.

One number can sound alarming out of context, so let me put it in perspective. Nearly 20 percent of people treated for PE die within 90 days, but in many of those cases the PE isn't the actual cause of death. These are often people who already had serious illnesses like advanced cancer, and the PE was a marker of how sick they were rather than what took their life. For an otherwise healthy person who gets diagnosed and treated promptly, the outlook is much better than that headline figure suggests.

Recovery and the long haul

Most people recover from a pulmonary embolism, but recovery isn't always a straight line, and I think it helps to know that in advance. About half of patients experience what's called post-PE syndrome in the year after the event, a lingering combination of reduced exercise tolerance, breathlessness on exertion, and a dip in quality of life. It's common, it's real, and it tends to improve with time and a gradual return to activity, often guided by cardiac rehabilitation.

A smaller but more serious long-term problem is chronic thromboembolic pulmonary hypertension, or CTEPH, where old clots don't fully clear and the lung arteries stay narrowed, raising the pressure the heart has to pump against. It affects roughly 1 to 4 percent of PE patients and is dangerous if left untreated, with a 25 to 30 percent risk of death within three years. The people most at risk are those with a prior PE, younger patients, those who had large clots, and those whose PE had no clear cause. The reason I mention it is that CTEPH is treatable, and often curable, with a specialized operation called pulmonary thromboendarterectomy that removes the old scarred clot. If you have ongoing breathlessness months after a PE, that deserves a closer look rather than being written off as deconditioning.

When to call 911

Call 911 or go to the nearest emergency room right away if you have sudden shortness of breath, sharp chest pain that's worse when you breathe in, a racing heart, you cough up blood, or you feel faint or pass out, especially if you also have a swollen, painful leg or any of the risk factors above such as recent surgery, a long trip, active cancer, or recent childbirth. A pulmonary embolism can be diagnosed and treated quickly, but only if you get evaluated. As with chest pain, the cost of coming in and being told you're fine is small, and the cost of staying home with a growing clot can be enormous.

Common Patient Questions

Is a pulmonary embolism the same as a heart attack?

No, though they can feel similar. A heart attack is a blockage in the arteries that feed the heart muscle. A pulmonary embolism is a blockage in the arteries that carry blood into the lungs, and the clot usually starts in a leg vein. They're different problems with different treatments, which is one reason the emergency room tests carefully rather than assuming.

How long will I need to be on blood thinners?

Usually at least three months, and often longer. The right duration depends on why the clot happened. A PE triggered by a temporary event like surgery may need a shorter course, while an unprovoked PE or one linked to an ongoing risk like cancer often calls for extended or indefinite treatment. This is a decision you and your doctor make together by weighing your clotting risk against your bleeding risk.

Can a pulmonary embolism go away on its own?

Your body does gradually break down clots, but a PE should never be left untreated on the assumption it will resolve. Without blood thinners, the clot can grow, more clots can form, and the risk of a life-threatening event is much higher. Treatment is what makes the natural healing safe.

Why did I get a PE when I'm otherwise healthy?

Between a third and a half of pulmonary embolisms happen with no obvious trigger. Sometimes there's a subtle contributor we uncover later, such as an inherited clotting tendency, and sometimes there simply isn't a clear reason. An unprovoked PE in an otherwise healthy person is real and worth treating fully, and it sometimes prompts a look for an underlying cause.

Will flying or long car trips be dangerous now?

Long periods of sitting still are a risk factor, so it's worth taking simple precautions on trips over about four hours, such as moving your legs, walking when you can, and staying hydrated. If you're on blood thinners, you're already substantially protected. Ask your doctor about your specific situation before a long trip, particularly soon after a PE.

I still feel short of breath months later. Is that normal?

Lingering breathlessness in the year after a PE is common and often part of post-PE syndrome, which tends to improve with a gradual, guided return to activity. But persistent shortness of breath should always be checked, because a small number of people develop CTEPH, a treatable condition where old clots keep the lung pressures high. Don't just push through it without telling your doctor.

References

1. Freund, Yonathan, Fleur Cohen-Aubart, and Ben Bloom. "Acute Pulmonary Embolism: A Review." JAMA 328, no. 13 (2022): 1336-1345.

2. Khan, Faizan, Tobias Tritschler, Susan R. Kahn, and Marc A. Rodger. "Venous Thromboembolism." Lancet 398, no. 10294 (2021): 64-77.

3. Di Nisio, Marcello, Nick van Es, and Harry R. Büller. "Deep Vein Thrombosis and Pulmonary Embolism." Lancet 388, no. 10063 (2016): 3060-3073.

4. Gregson, John, Stephen Kaptoge, Thomas Bolton, et al. "Cardiovascular Risk Factors Associated With Venous Thromboembolism." JAMA Cardiology 4, no. 2 (2019): 163-173.

5. Kahn, Susan R., and Kerstin de Wit. "Pulmonary Embolism." New England Journal of Medicine 387, no. 1 (2022): 45-57.

6. Creager, Mark A., Geoffrey D. Barnes, Jay Giri, et al. "2026 AHA/ACC/ACCP/ACEP/CHEST/SCAI/SHM/SIR/SVM/SVN Guideline for the Evaluation and Management of Acute Pulmonary Embolism in Adults." Journal of the American College of Cardiology (2026).

7. Zuin, Marco, and Walter Ageno. "Precision Diagnosis of Acute Pulmonary Embolism: Decision Rules, Biomarkers, and Imaging." Journal of the American College of Cardiology (2026).

Published on damianrasch.com. The above information was composed by Dr. Damian Rasch, drawing on individual insight and bolstered by digital research and writing assistance. The information is for educational purposes only and does not constitute medical advice.