Most cases of pulmonary edema are caused by failure of the heart's main chamber, the left ventricle. It can be brought on by an acute heart attack, severe ischemia, volume overload of the heart's left ventricle, and mitral stenosis. Non-heart-related pulmonary edema is caused by lung problems like pneumonia, an excess of intravenous fluids, some types of kidney disease, bad burns, liver disease, nutritional problems, and Hodgkin's disease. Non-heart-related pulmonary edema can also be caused by other conditions where the lungs do not drain properly, and conditions where the respiratory veins are blocked.

Early symptoms of pulmonary edema include:

• shortness of breath upon exertion
• sudden respiratory distress after sleep
• difficulty breathing, except when sitting upright
• coughing

In cases of severe pulmonary edema, these symptoms will worsen to:

• labored and rapid breathing
• frothy, bloody fluid containing pus coughed from the lungs (sputum)
• a fast pulse and possibly serious disturbances in the heart's rhythm (atrial fibrillation, for example)
• cold, clammy, sweaty, and bluish skin
• a drop in blood pressure resulting in a thready pulse