Pneumonia is an infection in one or both lungs. Bacteria, viruses, and fungi cause it.
The infection causes inflammation in the air sacs in your lungs, which are called alveoli. The alveoli fill with fluid or pus, making it difficult to breathe.
Symptoms of pneumonia
Pneumonia symptoms can be mild to life-threatening. They can include:
- coughing that may produce phlegm (mucus)
- sweating or chills
- shortness of breath that happens while doing normal activities or even while resting
- chest pain that’s worse when you breathe or cough
- feelings of tiredness or fatigue
- loss of appetite
- nausea or vomiting
Other symptoms can vary according to your age and general health:
- Children under 5 years old may have fast breathing or wheezing.
- Infants may appear to have no symptoms, but sometimes they may vomit, lack energy, or have trouble drinking or eating.
- Older people may have milder symptoms. They can also exhibit confusion or a lower than normal body temperature.