What is pneumonia?

Pneumonia is an infection of the lungs. Many different germs can cause pneumonia, including bacteria, viruses, and fungi. When you breathe in these germs, they can settle in the air sacs (alveoli) of your lungs. Deep in your lungs, the germs may grow and overcome your body's normal defenses.

After they become infected, the air sacs then fill with pus and mucus. This swelling (inflammation) of the air sacs makes them less stretchy and keeps oxygen from properly reaching your blood stream.

As you work harder to breathe and give your body oxygen, you can feel short of breath. The swelling also causes many of the other symptoms of pneumonia like cough, fever, and chest pain.

Signs and symptoms

The signs and symptoms of pneumonia can range from mild to serious. It depends on your age and what type of pneumonia you have. Some of the most common symptoms include:
- cough
- yellow-green phlegm (mucus)
- shortness of breath
- feeling very tired and unwell
- chest pain
- fever

Diagnosing pneumonia

Your doctor will do tests to confirm that you have pneumonia. Some of these tests may include:
- sputum tests (lab tests done on the mucus or phlegm that you cough up from your lungs)
- blood tests
- chest X-rays

Preventing pneumonia

Some of the germs that can cause pneumonia are easily spread from person to person. They are carried in the nose and throat of an infected person. When an infected person coughs, they spray drops of infected saliva (spit) into the air around them. A person who breathes in that air can get pneumonia.

There are things you can do to reduce your risk of getting pneumonia:
- wash your hands properly and often
- throw away used tissues
- don't share cups or eating utensils with people who are sick
- stay away from people who are sick
- get your flu shot each year
- get your pneumococcal shot (some people may need it every five years — ask your doctor)

Learn more about the various types of pneumonia by clicking here.
Download your own Pneumonia fact sheet by clicking here.

Page Last Updated: 01/05/2017