Some symptoms of fluid on the lung are dry cough, difficulty breathing when lying down, chest pain and shortness of breath, states Healthline. Some people with fluid on the lung have no symptoms and are diagnosed by physical examination or chest radiograph.
Fluid on the lung, also known as pleural effusion, occurs when there is an excessive buildup of fluid between the lung and the chest wall, states Healthline. Fluid on the lung can be caused by cancer, pneumonia, heart failure, liver disease and kidney disease. The doctor may insert a needle into the chest cavity to suction some of the fluid for analysis to find out the cause of the pleural effusion.