Pulmonary edema, a medical emergency, is an accumulation of fluid in the lungs. Most often a consequence of congestive heart failure, pulmonary edema typically occurs when the heart is unable to pump blood out through the arteries as quickly as it is returned to the heart through the veins.

Failure of the left side of the heart (left ventricle) causes blood to accumulate in the veins of the lungs (pulmonary veins), producing a dangerous rise in blood pressure within these veins. Sustained high pressure in the pulmonary veins eventually forces some fluid from the blood into the surrounding microscopic air sacs (alveoli), which transfer oxygen to the bloodstream. As the alveoli fill with fluid, they can no longer provide adequate amounts of oxygen to the body.

Symptoms, especially severe breathing difficulty, develop over the course of a few hours and may be life-threatening. Although the outlook for pulmonary edema is favorable if the underlying disorder is treated in a timely fashion, the overall outcome for the patient depends upon the nature of the underlying disorder. Adults at high risk for heart failure are most commonly affected.

A less common form of the disease, high-altitude pulmonary edema (which may occur while mountain-climbing, for instance), is also life-threatening if not treated quickly. Strenuous activity upon arrival at high altitudes may cause a dangerous rise in the pressure in the pulmonary veins, forcing fluid out of the veins into the alveoli. After people become acclimated to the altitude, strenuous activity does not pose such a risk.

High-altitude pulmonary edema most often affects young adults under age 25 who are unacclimatized to the altitude but otherwise in good health. Symptoms appear within 24 to 72 hours and necessitate immediate descent to a lower altitude for treatment. (Air travelers are generally not at risk for this disorder because commercial airplane cabins are pressurized.)

What Causes Pulmonary Edema?

  • Congestive heart failure due to high blood pressure, aortic or mitral valve disease, or cardiomyopathy is a common cause of pulmonary edema.
  • A heart attack may cause pulmonary edema.
  • A variety of other conditions, such as lung infections, extensive burns, liver or kidney disease, Hodgkin’s disease, pneumothorax or nutritional deficiencies, may lead to pulmonary edema in some cases.
  • Overdoses of heroin, morphine and other narcotics may lead to pulmonary edema.
  • Rapid ascent to high altitudes followed immediately by heavy exertion may cause high-altitude pulmonary edema.


Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference

Simeon Margolis, M.D., Ph.D., Medical Editor

Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at Healthcommunities.com

Published: 28 Aug 2011

Last Modified: 08 Sep 2015