Pneumonia is an inflammatory condition of the lung affecting primarily the microscopic air sacs known as alveoli.[4][13] Typical signs and symptoms include a varying severity and combination of productive or dry cough, chest pain, fever, and trouble breathing, depending on the underlying cause
Pneumonia is usually caused by infection with viruses or bacteria and less commonly by other microorganisms, certain medications and conditions such as autoimmune diseases.[4][5] Risk factors include other lung diseases such as cystic fibrosis, COPD, and asthma, diabetes, heart failure, a history of smoking, a poor ability to cough such as following a stroke, or a weak immune system.[6] Diagnosis is often based on the symptoms and physical examination. Chest X-ray, blood tests, and culture of the sputum may help confirm the diagnosis.[7] The disease may be classified by where it was acquired with community, hospital, or health care associated pneumonia.
Vaccines to prevent certain types of pneumonia are available. Other methods of prevention include handwashing and not smoking.[9] Treatment depends on the underlying cause.[15] Pneumonia believed to be due to bacteria is treated with antibiotics.[10] If the pneumonia is severe, the affected person is generally hospitalized.[15] Oxygen therapy may be used if oxygen levels are low