Pneumonia is swelling (inflammation) of the tissue in one or both lungs. It's usually caused by a bacterial infection. It can also be caused by a virus, such as coronavirus (COVID-19).
Symptoms of pneumonia
The symptoms of pneumonia can develop suddenly over 24 to 48 hours, or they may come on more slowly over several days.
Common symptoms of pneumonia include:
- a cough – which may be dry, or produce thick yellow, green, brown or blood-stained mucus (phlegm)
- difficulty breathing – your breathing may be rapid and shallow, and you may feel breathless, even when resting
- rapid heartbeat
- high temperature
- feeling generally unwell
- sweating and shivering
- loss of appetite
- chest pain – which gets worse when breathing or coughing
Less common symptoms include:
When to get medical help
If you feel unwell and have symptoms of pneumonia, contact your GP or use the 111 online service.
Only call 111 if you cannot get help online or you need help for a child under 5.
If you have a high temperature or you do not feel well enough to do your normal activities, try to stay at home and avoid contact with other people until you feel better.
Call 999 for an ambulance if you or someone you care for:
- are struggling to breathe
- are coughing up blood
- have blue lips or a blue face
- feel cold and sweaty, with pale or blotchy skin
- have a rash that does not fade when you roll a glass over it
- collapse or faint
- become confused or very drowsy
- have stopped peeing or are peeing much less than usual
Pneumonia can affect people of any age, but it's more common, and can be more serious, in certain groups of people, such as the very young or the elderly.
People in these groups are more likely to need hospital treatment if they develop pneumonia.
What causes pneumonia
Pneumonia is usually the result of a bacterial infection.
As well as bacterial pneumonia, other types include:
- viral pneumonia – caused by a virus, such as coronavirus
- aspiration pneumonia – caused by breathing in vomit, a foreign object, such as a peanut, or a harmful substance, such as smoke or a chemical
- fungal pneumonia – rare in the UK and more likely to affect people with a weakened immune system
- hospital-acquired pneumonia – pneumonia that develops in hospital while being treated for another condition or having an operation; people in intensive care on breathing machines are particularly at risk of developing ventilator-associated pneumonia
The following groups have an increased risk of developing pneumonia:
- babies and very young children
- elderly people
- people who smoke
- people with other health conditions, such as asthma, cystic fibrosis, or a heart, kidney or liver condition
- people with a weakened immune system – for example, as a result of a recent illness, such as flu, having HIV or AIDS, having chemotherapy, or taking medicine after an organ transplant
A doctor may be able to diagnose pneumonia by asking about your symptoms and examining your chest.
Further tests may be needed in some cases.
To help make a diagnosis, a doctor may ask you:
- whether you feel breathless or you're breathing faster than usual
- how long you have had your cough, and whether you're coughing up mucus and what colour it is
- if the pain in your chest is worse when you breathe in or out
A doctor may also take your temperature and listen to your chest and back with a stethoscope to check for any crackling or rattling sounds.
They may also listen to your chest by tapping it. Lungs filled with fluid produce a different sound from normal healthy lungs.
If you have mild pneumonia, you probably will not need to have a chest X-ray or any other tests.
You may need a chest X-ray or other tests, such as a sputum (mucus) test or blood tests, if your symptoms have not improved within 48 hours of starting treatment.
Mild pneumonia can usually be treated at home by:
- getting plenty of rest
- taking antibiotics if the pneumonia is likely to be caused by a bacterial infection
- drinking plenty of fluids
If you do not have any other health problems, you should respond well to treatment and soon recover, although your cough may last for some time.
For at-risk groups, pneumonia can be severe and may need to be treated in hospital.
This is because it can lead to serious complications, which in some cases can be fatal, depending on a person's health and age.
Complications of pneumonia
Complications of pneumonia are more common in young children, the elderly and those with pre-existing health conditions, such as diabetes.
Possible complications of pneumonia include:
- pleurisy – where the thin linings between your lungs and ribcage (pleura) become inflamed, which can lead to respiratory failure
- a lung abscess – a rare complication that's mostly seen in people with a serious pre-existing illness or a history of severe alcohol misuse
- blood poisoning (sepsis) – also a rare but serious complication
You'll be admitted to hospital for treatment if you develop one of these complications.
Although most cases of pneumonia are bacterial and are not passed on from one person to another, ensuring good standards of hygiene will help prevent germs spreading.
For example, you should:
- cover your mouth and nose with a handkerchief or tissue when you cough or sneeze
- throw away used tissues immediately – germs can live for several hours after they leave your nose or mouth
- wash your hands regularly to avoid transferring germs to other people or objects
A healthy lifestyle can also help prevent pneumonia. For example, you should stop smoking as it damages your lungs and increases the chance of infection.
Excessive and prolonged alcohol misuse also weakens your lungs' natural defences against infections, making you more vulnerable to pneumonia.
Page last reviewed: 30 June 2019
Next review due: 30 June 2022