Pneumonia is an infection or inflammation of the lungs that results in the lungs’ air sacs becoming filled with fluid. Pneumonia can affect one or both lungs. It is a common condition that affects millions of people in the United States every year.

Pneumonia is caused when a germ enters the respiratory system and is not attacked effectively by the body’s natural defenses. If the germ enters the lungs, it can cause the air sacs of the lungs to fill with fluid as the immune system attempts to fight the infection. This can decrease the amount of oxygen that enters the bloodstream and impairs the body from working effectively.

Some types of pneumonia are mild and can be treated with rest and extra fluids. However, other types of pneumonia can be very serious and require medical treatment. People with weakened immune systems caused by certain factors are more at risk, including:

• Infants and children
  
  
• Older adults
  
  
• People with HIV, AIDS or other illnesses that can affect the immune system
  
  
• People who are hospitalized to recover from other illnesses

There are many different types of pneumonia that can be caused by a variety of microorganisms, including:

• Bacteria
• Viruses
• Fungi
• Parasites
• Toxins from other parts of the body
• Chemical toxins

Pneumonia produces a variety of symptoms depending on the germ that caused the infection. The most common symptoms of pneumonia are a persistent cough, discolored phlegm (mucus) and a fever with shaking chills. Other symptoms may include headache, fatigueand shortness of breath.

Pneumonia can usually be diagnosed after a medical history, physical examination and chest x-ray. Sometimes other tests such as blood tests or sputum cultures may be required. Pneumonia that has been caused by bacteria can be treated with antibiotics. Other types of pneumonia do not respond to antibiotics and are generally treated at home with plenty of fluids, adequate rest and over-the-counter medicines to reduce fever and suppress a cough.