Lung infection is an infection caused by inflammation of the air sacs in the lungs due to bacteria, viruses, or fungi, resulting in their filling with fluid or pus. This can make it difficult for inhaled oxygen to enter the bloodstream. The most common lung infection arising from infections in the upper and lower respiratory tract is pneumonia. Besides pneumonia, bronchitis, an infection of the bronchial tubes that carry air to the lungs, is also among these infections.

Lung infection, accompanied by symptoms that disrupt a person's daily life, can lead to serious complications and become dangerous. Therefore, symptoms should be taken seriously, and a doctor should be consulted for treatment of a lung infection.