What Is Pneumonia?
Pneumonia is an infection in one or both of the lungs. Many small germs, such as bacteria, viruses, and fungi, can cause pneumonia. The infection causes your lungs’ air sacs, called alveoli to become inflamed. The air sacs may fill up with fluid or pus, causing symptoms such as a cough (with phlegm), fever, chills, and trouble breathing.
Pneumonia and its symptoms can vary from mild to severe. Many factors affect how serious pneumonia is, such as the type of germ causing the infection and your age and overall health.