Pneumonia is inflammation of the tissues in one or both of your lungs. It's usually caused by an infection.
At the end of the airways in your lungs there are clusters of tiny air sacs called alveoli. 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.
How common is pneumonia?
In the UK, pneumonia affects up to 11 in 1,000 adults each year. It's more common during autumn and winter.
Pneumonia can affect people of any age. However, in some groups of people it's more common and can be more serious. For example:
- babies, young children and elderly people,
- people who smoke, and
- people with other health conditions, such as a lung condition or a lowered immune system.
People in these groups are also more likely to need treatment in hospital.
How serious is pneumonia?
Some forms of pneumonia can be more severe than others, depending on the cause.
Mild pneumonia can usually be treated at home. People who are otherwise healthy usually recover well. However, complications can develop.
For people with other health conditions, pneumonia can be severe and may need to be treated in hospital.
Sometimes pneumonia can be fatal.
Immune The immune system is the body's defence system. It helps protect the body from disease, bacteria and viruses.
Bacteria Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and some others are good for you.
Vomit
Vomiting is when you bring up the contents of your stomach through your mouth.
Lungs
Lungs are a pair of organs in the chest that control breathing. They remove carbon dioxide from the blood and replace it with oxygen.
Inflammation Inflammation is the body's response to infection, irritation or injury. It causes redness, swelling, pain and sometimes a feeling of heat in the affected area.
