1 Some toxins may also increase mucus production in the lining of the lungs. 2  Autoimmune diseases like sarcoidosis may cause fluid in the lungs due to the inflammation of the lung tissue.  Shortage of oxygen due to high altitudes, COPD (chronic obstructive pulmonary disease) and suffocation may result in pulmonary edema.
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While pneumonia can lead to fluid building up in the lungs, water in the lungs is not a cause of pneumonia, according to Mayo Clinic and the American Lung Association. Viruses, bacteria, mycoplasmas, fungi and other infectious agents, and certain chemicals all potentially cause pneumonia. Full Answer >.
https://www.reference.com/health/causes-fluid-lungs-f1b3657eaef3d48b
1 Oxygen is administered in severe cases of fluid in the lungs where proper gas exchange is impaired. While this does not immediately treat the cause of fluid in the lungs, except in a shortage of oxygen, it assists with adequate gas exchange.  Physiotherapy may be necessary to assist with mucus drainage.
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High altitude may increase pressure in the pulmonary capillaries and forces fluid into the alveoli. Pulmonary embolisms, nervous system dysfunctions, reactions to toxic substances, adverse drug reactions, severe smoke inhalation and near drowning also cause fluid in the lungs, explains Mayo Clinic.
https://www.reference.com/health/causes-fluid-lungs-f1b3657eaef3d48b
Removing the fluid (thoracentesis) may be done if there is a lot of fluid and it is causing chest pressure, shortness of breath, or other breathing problems, such as a low oxygen level. Removing the fluid allows the lung to expand, making breathing easier. The cause of the fluid buildup must also be treated. If it is due to congestive heart failure, you may receive diuretics (water pills) and other medications to treat heart failure. Pleural effusion caused by infection is treated with antibiotics.
https://medlineplus.gov/ency/article/000086.htm
There are multiple causes of fluid in the lungs and many of them relate to the heart, notes Mayo Clinic. When the left ventricle is unable to efficiently pump out the blood it receives from the pulmonary circulation, pressure occurs in the left atrium, the veins and eventually the capillaries in the lungs.
https://www.reference.com/health/causes-fluid-lungs-f1b3657eaef3d48b
There are many conditions that cause water or fluid in the lungs, according to Mayo Clinic, but most are related to the heart and a condition known as cardiogenic pulmonary edema. Other causes include high altitudes, drug reactions and exposure to toxins.
https://www.reference.com/health/causes-fluid-lungs-f1b3657eaef3d48b
Fluid in the lungs is a broad term to describe two possible conditions that may give characteristic symptoms, like a bubbling sound in the lungs (rales) when breathing. The fluid accumulation may be inside the lung (pulmonary edema) or outside the lung (pleural effusion), in the space between the lung and chest wall.
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Treatment is dependent on the cause of the fluid in the lungs. Some of the treatment options may include 1  : Antibiotics, antivirals or antifungals may be necessary in the case of an infection.  Diuretics assist with passing out additional fluid but should be used cautiously in the case of cardiac diseases.
http://www.healthhype.com/fluid-in-the-lungs-causes-and-treatment.html
1 Renal failure may cause pulmonary edema as the kidneys are unable to filter out toxins in the blood. 2  Smoke inhalation may cause severe inflammation of the lung tissue, which results in fluid accumulation in the lungs.  Lymphatic insufficiency result in inadequate drainage of lymph fluid.
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causes of lung fluid
  The causes of lung fluid is Sarcoidosis. Sarcoidosis can cause  lung fluid.