Short of Breath? Why an Embolism Occurs and Your Vital Medical Next Steps

Feeling suddenly short of breath can be frightening. While many causes are mild—like anxiety, asthma, or a respiratory infection—one serious cause you should know about is an embolism, specifically a pulmonary embolism.

A pulmonary embolism happens when a blood clot (or other material) travels through the bloodstream and blocks an artery in the lungs. This blockage can reduce oxygen levels, strain the heart, and in severe cases, become life-threatening. The good news is that when recognized early, an embolism is treatable.

This guide explains why an embolism occurs, the warning signs, who is at risk, and what steps you should take next.

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What Is an Embolism?

An embolism occurs when something—usually a blood clot—travels through the bloodstream and blocks a blood vessel.

There are different types of embolism, depending on where the blockage happens:

• Pulmonary embolism (PE) – blockage in the lungs
• Cerebral embolism – blockage in the brain (can cause stroke)
• Coronary embolism – blockage in heart arteries
• Peripheral embolism – blockage in limbs

The most common and widely discussed type is pulmonary embolism, which we'll focus on here because shortness of breath is a key symptom.

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Why Does a Pulmonary Embolism Occur?

Most pulmonary embolisms start as a deep vein thrombosis (DVT)—a blood clot that forms in a deep vein, usually in the leg.

If part of that clot breaks loose, it can travel:

1. From the leg vein
2. Through the right side of the heart
3. Into the pulmonary arteries
4. Where it becomes lodged in the lungs

This blockage prevents normal blood flow and oxygen exchange.

Why Do Blood Clots Form?

Blood clots tend to form when one or more of the following occur:

• Slowed blood flow (such as during long periods of sitting or bed rest)
• Damage to blood vessel walls
• Increased clotting tendency (genetic or acquired)

Doctors often refer to this as Virchow's Triad—the three main factors that increase clot risk.

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Risk Factors for Embolism

An embolism can happen to anyone, but certain conditions increase risk:

Situational Risks

• Long flights or car rides (4+ hours)
• Recent surgery (especially orthopedic surgery)
• Prolonged bed rest or hospitalization
• Major injury

Medical Risks

• Previous DVT or pulmonary embolism
• Cancer
• Heart disease
• Obesity
• Smoking
• Pregnancy or recent childbirth
• Hormonal birth control or hormone replacement therapy
• Certain inherited clotting disorders

Having one or more of these risk factors does not mean you will develop an embolism—but it does mean symptoms should be taken seriously.

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Symptoms of a Pulmonary Embolism

Symptoms can vary from mild to severe. Some embolisms are small and cause subtle signs. Others are large and cause sudden, severe symptoms.

Common symptoms include:

• Sudden shortness of breath
• Sharp chest pain (often worse with deep breathing)
• Rapid heartbeat
• Cough (sometimes with blood)
• Lightheadedness or fainting
• Anxiety or a sense that "something isn't right"

You may also notice signs of a deep vein thrombosis in the leg before a pulmonary embolism develops:

• Swelling in one leg
• Pain or tenderness in the calf
• Warmth in the affected area
• Red or discolored skin

Not everyone has leg symptoms. In some cases, shortness of breath is the first sign.

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How Serious Is an Embolism?

A pulmonary embolism is a medical emergency. Large clots can:

• Block major blood flow to the lungs
• Cause low oxygen levels
• Strain or damage the heart
• Lead to shock or cardiac arrest

However, many embolisms are treatable when caught early. Modern treatments significantly reduce complications and death rates.

The key is rapid medical evaluation.

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What Should You Do If You Suspect an Embolism?

If you experience:

• Sudden unexplained shortness of breath
• Chest pain with breathing
• Fainting
• Rapid heart rate

You should seek immediate medical attention.

Call emergency services if symptoms are severe or sudden. Do not attempt to "wait it out."

If your symptoms are milder but concerning—especially if you have risk factors—contact a doctor promptly.

If you're unsure whether your symptoms warrant urgent care, you can start by using a free Pulmonary Embolism symptom checker to quickly assess your risk level and understand whether you need immediate medical evaluation.

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How Is an Embolism Diagnosed?

Doctors use a combination of:

1. Medical History and Physical Exam

They'll ask about:

• Recent travel or surgery
• Leg symptoms
• Personal or family clot history

2. Blood Tests

• D-dimer test – detects clot breakdown products

3. Imaging Tests

• CT pulmonary angiography (most common)
• Ventilation-perfusion (V/Q) scan
• Ultrasound of the legs
• Echocardiogram (in some cases)

Diagnosis must be confirmed with proper imaging. Self-diagnosis is not reliable.

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Treatment for Pulmonary Embolism

Treatment depends on the size of the clot and your overall stability.

Common Treatments Include:

✅ Anticoagulants (Blood Thinners)

These prevent existing clots from growing and reduce new clot formation.

• Often the first-line treatment
• May be taken for 3–6 months or longer

✅ Thrombolytics (Clot-Busting Drugs)

• Used in severe cases
• Dissolve large clots quickly
• Higher bleeding risk

✅ Surgical or Catheter-Based Removal

• For life-threatening cases
• Removes or breaks up the clot directly

Most patients recover fully with appropriate treatment, though some may develop long-term complications such as chronic thromboembolic pulmonary hypertension (CTEPH), a rare but serious condition.

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Can Embolism Be Prevented?

Yes—especially if you have risk factors.

Prevention Strategies:

• Move frequently during long trips (walk every 1–2 hours)
• Stay hydrated
• Wear compression stockings if advised
• Follow post-surgery mobility instructions
• Take prescribed blood thinners as directed
• Maintain a healthy weight
• Stop smoking
• Discuss clot risk with your doctor before starting hormonal medications

If you've had a prior embolism, long-term prevention planning with your physician is essential.

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When Shortness of Breath Is NOT an Embolism

It's important to stay balanced.

Shortness of breath is common and often caused by:

• Anxiety or panic attacks
• Asthma
• Respiratory infections
• Allergies
• Deconditioning
• Heartburn

That said, if breathing difficulty is new, unexplained, or severe, it should always be evaluated.

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The Bottom Line

An embolism, particularly a pulmonary embolism, is a serious condition that occurs when a blood clot blocks blood flow in the lungs. It can develop quickly and may become life-threatening without treatment.

Key points to remember:

• Sudden shortness of breath should never be ignored
• Risk factors increase suspicion
• Early treatment dramatically improves outcomes
• Prevention is possible in many cases

If you are unsure whether your symptoms could be related to an embolism, consider starting with a free online Pulmonary Embolism symptom checker and then promptly speak to a doctor about your results.

If symptoms are severe, sudden, or worsening, seek emergency care immediately.

Your health and safety come first. Prompt action can save lives.