Pneumonia is an infection that inflames the air sacs in one or both lungs. The air sacs may fill with fluid or pus (purulent material), causing cough with phlegm or pus, fever, chills, and difficulty breathing. A variety of organisms, including bacteria, viruses, and fungi can cause pneumonia.

Pneumonia can range in seriousness from mild to life-threatening. It is most serious for infants and young children, people older than age 65, and people with health problems or weakened immune systems.

1. Chest pain when you breathe or cough

2. Confusion or changes in mental awareness (in adults age 65 and older)

3. Cough, which may produce phlegm

4. Fatigue

5. Fever, sweating, and shaking chills

6. Lower than normal body temperature (in adults older than age 65 and people with weak immune systems)

7. Shortness of breath