Pneumonia is inflammation (swelling) of the tissue in one or both of your lungs. It is usually caused by an infection.
At the end of the breathing tubes in your lungs there are clusters of tiny air sacs. If you have pneumonia, these tiny sacs become inflamed and fill up with fluid.
As well as making you cough, the inflammation makes it harder for you to breathe. It also means your body is less able to absorb oxygen. For more information, see Pneumonia - symptoms.
Terms such as bronchopneumonia, lobar pneumonia and double pneumonia are sometimes used, but refer to the same condition with the same causes and treatment.
How common is pneumonia?
In the UK, pneumonia affects up to 11 in 1,000 adults each year. It is more common during autumn and winter.
Pneumonia can affect people of any age, although it is more common and can be more serious in groups such as:
- babies, young children and elderly people
- people who smoke
- people with other health conditions, such as a lung condition or a weakened immune system
For more information, see People at risk.
People in these groups are more likely to need treatment in hospital.
Outlook
Some forms of pneumonia can be more severe than others, depending on the cause.
For people with other health conditions, pneumonia can be severe and may need to be treated in hospital.
This is because there are a number of complications that can accompany pneumonia, some of which can be fatal, depending on the health and age of the patient. These include respiratory failure, (when the lungs cannot take in enough oxygen) due to the air sacs filling with water, as well as lung abscesses and septicaemia. For more information see Pneumonia - complications.
Mild pneumonia can usually be treated at home with antibiotics (see Pneumonia - treatment). People who are otherwise healthy usually recover well. However, complications can still develop.
