Pneumonia is a lung infection that can range from mild to so serious that you have to go to the hospital. It happens when an infection causes air sacs in your lungs (the alveoli) and tubes in your ...

Generally, those at greatest risk for serious complications from pneumonia have a weaker immune system or a condition or lifestyle factor that affects their lungs. Pneumonia is an infection of the ...

Pneumonia typically occurs when a person acquires a viral, bacterial, or fungal lung infection. A cough is a common symptom of pneumonia. However, a person can have the condition without a cough.