Pulmonary edema is a condition caused by excess fluid in the lungs. This fluid collects in the numerous air sacs in the lungs, making it difficult to breathe.

In most cases, heart problems cause pulmonary edema. But fluid can collect in the lungs for other reasons, including pneumonia, exposure to certain toxins and medications, trauma to the chest wall, and traveling to or exercising at high elevations.

Pulmonary edema that develops suddenly (acute pulmonary edema) is a medical emergency requiring immediate care. Pulmonary edema can sometimes cause death. The outlook improves if you get treated quickly. Treatment for pulmonary edema varies depending on the cause but generally includes supplemental oxygen and medications.


Pulmonary edema signs and symptoms may appear suddenly or develop over time. The signs and symptoms you have depends on the type of pulmonary edema.

Sudden (acute) pulmonary edema signs and symptoms

  • Difficulty breathing (dyspnea) or extreme shortness of breath that worsens with activity or when lying down
  • A feeling of suffocating or drowning that worsens when lying down
  • A cough that produces frothy sputum that may be tinged with blood
  • Wheezing or gasping for breath
  • Cold, clammy skin
  • Anxiety, restlessness or a sense of apprehension
  • Bluish lips
  • A rapid, irregular heartbeat (palpitations)

Long-term (chronic) pulmonary edema signs and symptoms

  • Difficulty breathing with activity or when lying flat
  • Awakening at night with a cough or breathless feeling that may be relieved by sitting up
  • More shortness of breath than normal when you're physically active
  • Wheezing
  • Rapid weight gain
  • Swelling in your lower extremities
  • Fatigue
  • New or worsening cough

High-altitude pulmonary edema (HAPE) signs and symptoms

HAPE can occur in adults and children who travel to or exercise at high altitudes. Signs and symptoms are similar to those that occur with acute pulmonary edema and can include:

  • Headache, which may be the first symptom
  • Shortness of breath with activity, which worsens to shortness of breath at rest
  • Decreased ability to exercise as you once could
  • Dry cough, at first
  • Later, a cough that produces frothy, pink sputum
  • A very fast heartbeat (tachycardia)
  • Weakness
  • Chest pain
  • Low-grade fever

Signs and symptoms of high-altitude pulmonary edema (HAPE) tend to get worse at night.

When to see a doctor

Pulmonary edema that comes on suddenly (acute pulmonary edema) is life-threatening. Call 911 or emergency medical help if you have any of the following acute signs and symptoms:

  • Shortness of breath, especially if it comes on suddenly
  • Trouble breathing or a feeling of suffocating (dyspnea)
  • A bubbly, wheezing or gasping sound when you breathe
  • Pink, frothy sputum when you cough
  • Breathing difficulty along with a lot of sweating
  • A blue or gray color to your skin
  • Confusion
  • A significant drop in blood pressure resulting in lightheadedness, dizziness, weakness or sweating
  • A sudden worsening of any of pulmonary edema symptoms

Don't attempt to drive yourself to the hospital. Instead, call 911 or emergency medical care and wait for help.


The causes of pulmonary edema vary. Pulmonary edema is grouped into two categories, depending on where the problem started.

  • If a heart problem causes the pulmonary edema, it's called cardiogenic pulmonary edema. Most often, the fluid buildup in the lungs is due to a heart condition.
  • If pulmonary edema is not heart related, it's called noncardiogenic pulmonary edema.
  • Sometimes, pulmonary edema can be caused by both a heart problem and a non-heart problem.

Understanding the relationship between your lungs and your heart can help explain why pulmonary edema may occur.

How your lungs work

Your lungs contain many small, elastic air sacs called alveoli. With each breath, these air sacs take in oxygen and release carbon dioxide. Normally, this exchange of gases occurs without problems.

But sometimes, the alveoli fill with fluid instead of air, preventing oxygen from being absorbed into your bloodstream.

How your heart works

Your heart is made of two upper and two lower chambers. The upper chambers (the right and left atria) receive incoming blood and pump it into the lower chambers (right and left ventricles). The lower chambers pump blood out of your heart.

Normally, deoxygenated blood from all over your body enters the right atrium then the right ventricle, where it's pumped through large blood vessels (pulmonary arteries) to your lungs. There, the blood releases carbon dioxide and picks up oxygen as it flows by the alveoli.

The oxygen-rich blood then returns to the left atrium through the pulmonary veins, flows through the mitral valve into the left ventricle and finally leaves your heart through the largest blood vessel in the body, called the aorta.

The heart valves keep blood flowing in the correct direction. The aortic valve keeps the blood from flowing backward into your heart. From the aorta, the blood travels to the rest of your body.

Heart-related (cardiogenic) pulmonary edema

Cardiogenic pulmonary edema is caused by increased pressures in the heart.

It's usually a result of heart failure. When a diseased or overworked left ventricle can't pump out enough of the blood it gets from your lungs, pressures in the heart go up. The increased pressure pushes fluid through the blood vessel walls into the air sacs.

Medical conditions that can cause heart failure and lead to pulmonary edema include:

  • Coronary artery disease. Over time, the arteries that supply blood to your heart muscle can become narrow from fatty deposits (plaques). A slow narrowing of the coronary arteries can make the left ventricle weak. Sometimes, a blood clot forms in one of these narrowed arteries, blocking blood flow and damaging part of your heart muscle, resulting in a heart attack. A damaged heart muscle can no longer pump as well as it should.
  • Cardiomyopathy. This term means heart muscle damage. If you have cardiomyopathy, your heart has to pump harder, and pressures go up. The heart may be unable to respond to conditions that require it to work harder, such as exercise, infection or a rise in blood pressure. When the left ventricle can't keep up with the demands that are placed on it, fluid backs up into your lungs.
  • Heart valve problems. Narrowing of the aortic or mitral heart valves (stenosis) or a valve that leaks or doesn't close properly affects blood flow into the heart. The heart has to work harder, and pressures go up. If valve leakage develops suddenly, you may develop sudden and severe pulmonary edema.
  • High blood pressure (hypertension). Untreated or uncontrolled high blood pressure can enlarge the heart.
  • Other heart problems. Inflammation of the heart muscle (myocarditis), congenital heart defects and abnormal heart rhythms (arrhythmias) also may cause pulmonary edema.
  • Kidney disease. High blood pressure due to narrowed kidney arteries (renal artery stenosis) or fluid buildup due to kidney disease can cause pulmonary edema.
  • Chronic health conditions. Thyroid disease and a buildup of iron (hemochromatosis) or protein (amyloidosis) also may contribute to heart failure and cause pulmonary edema.

Non-heart-related (noncardiogenic) pulmonary edema

Pulmonary edema that is not caused by increased pressures in your heart is called noncardiogenic pulmonary edema.

Causes of noncardiogenic pulmonary edema include:

  • Acute respiratory distress syndrome (ARDS). This serious disorder occurs when your lungs suddenly fill with fluid and inflammatory white blood cells. Many conditions can cause ARDS, including severe injury (trauma), widespread infection (sepsis), pneumonia and severe bleeding.
  • Adverse drug reaction or drug overdose. Many drugs — ranging from aspirin to illegal drugs such as heroin and cocaine — are known to cause pulmonary edema.
  • Blood clot in the lungs (pulmonary embolism). If a blood clot travels from the blood vessels in your legs to your lungs, you can develop pulmonary edema.
  • Exposure to certain toxins. Inhaling toxins or breathing in some of your stomach contents when you vomit (aspiration) causes intense irritation of the small airways and alveoli, resulting in fluid buildup.
  • High altitudes. Pulmonary edema has been seen in mountain climbers, skiers, hikers and other people who travel to high elevations, usually above 8,000 feet (about 2,400 meters). High-altitude pulmonary edema (HAPE) generally occurs in those who don't first become acclimated to the elevation (which can take from a few days to a week or so). But people who live at high altitudes can get HAPE with no elevation change if they have a respiratory infection.
  • Near drowning. Inhaling water causes fluid buildup in the lungs that is reversible with immediate medical care.
  • Negative pressure pulmonary edema. Pulmonary edema can develop after a blockage in the upper airway causes negative pressure in the lungs from intense efforts to breathe despite the blockage. With treatment, most people with this type of pulmonary edema recover in about 24 hours.
  • Nervous system conditions or procedures. A type of pulmonary edema called neurogenic pulmonary edema can occur after a head injury, seizure or brain surgery.
  • Smoke inhalation. Smoke from a fire contains chemicals that damage the membrane between the air sacs and the capillaries, allowing fluid to enter your lungs.
  • Transfusion-related lung injury. Blood transfusions may cause fluid overload in the left ventricle, leading to pulmonary edema.
  • Viral infections. Pulmonary edema can be caused by viruses such as the hantavirus and dengue virus.

Risk factors

Heart failure and other heart conditions that raise pressure in the heart increase the risk of pulmonary edema. Risk factors for heart failure include:

  • Abnormal heart rhythms (arrhythmias)
  • Alcohol use
  • Congenital heart disease
  • Coronary artery disease
  • Diabetes
  • Heart valve disease
  • High blood pressure
  • Sleep apnea

However, some nervous system conditions and lung damage due to near drowning, drug use, smoke inhalation, viral infections and blood clots also raise your risk.

People who travel to high-altitude locations above 8,000 feet (about 2,400 meters) are more likely to develop high-altitude pulmonary edema (HAPE). It usually affects those who do not first become acclimated to the elevation (which can take from a few days to a week or so).

Children who have existing pulmonary hypertension and structural heart defects may be more likely to get HAPE.


Complications depend on the underlying cause.

In general, if pulmonary edema continues, the pressure in the pulmonary artery can go up (pulmonary hypertension). Eventually, the heart becomes weak and begins to fail, and pressures in the heart and lungs go up.

Complications can include:

  • Breathing difficulty
  • Swelling of the legs, feet and abdomen
  • Buildup of fluid in the membranes that surround your lungs (pleural effusion)
  • Congestion and swelling of the liver

Immediate treatment is necessary for acute pulmonary edema to prevent death.


You may be able to prevent pulmonary edema by managing existing heart or lung conditions and following a healthy lifestyle.

For example, you can reduce your risk of many kinds of heart problems by taking steps to control your cholesterol and blood pressure. Follow these tips to keep your heart healthy:

  • Eat a healthy diet rich in fresh fruits, vegetables, whole grains, fat-free or low-fat dairy, and a variety of proteins.
  • Manage your weight.
  • Get regular exercise.
  • Don't smoke.
  • Limit salt and alcohol.
  • Manage stress.

Preventing high-altitude pulmonary edema (HAPE)

To prevent HAPE, gradually ascend to high elevations. Although recommendations vary, most experts advise increasing elevation no more than 1,000 to 1,200 feet (about 300 to 360 meters) a day once you reach 8,200 feet (about 2,500 meters).

Some climbers take prescription medications such as acetazolamide or nifedipine (Adalat CC, Procardia) to help prevent signs and symptoms of HAPE. To prevent HAPE, start taking the medication at least one day before ascent. Ask your doctor how long you need to take the medication after you've arrived at your high-altitude destination.

Nov. 17, 2021
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