Pneumonia is swelling (inflammation) of the tissue in one or both lungs. It's usually caused by a bacterial infection.

At the end of the breathing tubes in your lungs are clusters of tiny air sacs.

If you have pneumonia, these tiny sacs become inflamed and fill up with fluid.

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:

• coughing up blood (haemoptysis)
• headaches
• fatigue
• feeling sick or being sick
• wheezing
• joint and muscle pain
• feeling confused and disorientated, particularly in elderly people

When to see your GP

See your GP if you feel unwell and you have typical symptoms of pneumonia.

Seek urgent medical attention if you're experiencing severe symptoms, such as rapid breathing, chest pain or confusion.

Who's affected?

In the UK, pneumonia affects around 0.5 to 1% of adults each year. It's more widespread in autumn and winter.

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 pneumococcal infection, caused by bacteria called Streptococcus pneumoniae.

Many different types of bacteria, including Haemophilus influenzae and Staphylococcus aureus, can also cause pneumonia, as well as viruses and, more rarely, fungi.

As well as bacterial pneumonia, other types include:

• viral pneumonia – most commonly caused by the respiratory syncytial virus (RSV) and sometimes influenza type A or B; viruses are a common cause of pneumonia in young children
• 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

Risk groups

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 medication following an organ transplant

Diagnosing pneumonia

Your GP may be able to diagnose pneumonia by asking about your symptoms and examining your chest.

Further tests may be needed in some cases.

Pneumonia can be difficult to diagnose because it shares many symptoms with other conditions, such as the common cold, bronchitis and asthma.

To help make a diagnosis, a GP may ask you:

• whether you feel breathless or you're breathing faster than usual
• how long you've 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 GP 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 won't 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 haven't improved within 48 hours of starting treatment.

Treating pneumonia

Mild pneumonia can usually be treated at home by:

• getting plenty of rest
• taking antibiotics
• 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.

It's usually safe for someone with pneumonia to be around others, including family members.

But people with a weakened immune system are less able to fight off infections, so it's best they avoid close contact with a person with pneumonia.

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 (septicaemia) – also a rare but serious complication

You'll be admitted to hospital for treatment if you develop one of these complications.

Preventing pneumonia

Although most cases of pneumonia are bacterial and aren't 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 avoid smoking as it damages your lungs and increases the chance of infection.

Find out how to stop smoking.

Excessive and prolonged alcohol misuse also weakens your lungs' natural defences against infections, making you more vulnerable to pneumonia.

People at high risk of pneumonia should be offered the pneumococcal vaccine and flu vaccine.

Mild pneumonia can usually be treated at home with rest, antibiotics and by drinking plenty of fluids. More severe cases may need hospital treatment.

Unless a healthcare professional tells you otherwise, you should always finish taking a prescribed course of antibiotics, even if you feel better.

If you stop taking an antibiotic part way through a course, the bacteria can become resistant to the antibiotic.

After starting treatment, your symptoms should steadily improve.

However, how quickly they improve will depend on how severe your pneumonia is.

As a general guide, after:

• one week – high temperature shouls have gone
• four weeks – chest pain and mucus production should have substantially reduced
• six weeks – cough and breathlessness should have substantially reduced
• three months – most symptoms should have resolved, but you may still feel very tired (fatigue)
• six months – most people will feel back to normal

Treatment at home

Visit your GP if your symptoms don't improve within three days of starting antibiotics.

Symptoms may not improve if:

• the bacteria causing the infection is resistant to antibiotics – your GP may prescribe a different antibiotic, or they may prescribe a second antibiotic for you to take with the first one
• a virus is causing the infection, rather than bacteria – antibiotics have no effect on viruses, and your body's immune system will have to fight the viral infection by creating antibodies

Painkillers, such as paracetamol or ibuprofen, may help relieve pain and reduce fever.

However, you shouldn't take ibuprofen if you:

• are allergic to aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs)
• have asthma, kidney disease, a history of stomach ulcers or indigestion

Cough medicines aren't recommended as there's also little evidence they are effective. A warm honey and lemon drink can help relieve discomfort caused by coughing.

Your cough may persist for two to three weeks after you finish your course of antibiotics, and you may feel tired for even longer as your body continues to recover.

Drink plenty of fluids to avoid dehydration, and get plenty of rest to help your body recover.

If you smoke, it's more important than ever to stop, as smoking damages your lungs.

Read more about stop smoking treatments and how to stop smoking.

See your GP if, after following the above self-help measures, your condition is deteriorating or isn't improving as expected.

Follow-up

Your GP will probably arrange a follow-up appointment for you about six weeks after you start your course of antibiotics.

In some cases, they may arrange follow-up tests, such as a chest X-ray, if:

• your symptoms haven't improved
• your symptoms have come back
• you smoke
• you're over the age of 50

Some people may be advised to have a flu vaccination or pneumococcal vaccination after recovering from pneumonia.

Treatment in hospital

You may need treatment in hospital if your symptoms are severe. You'll be given antibiotics and fluids intravenously through a drip, and you may need oxygen to help breathing.

You will probably not be given antibiotics if the cause is likely to be a virus, such as coronavirus. This is because antibiotics do not work for viral infections.

You may also be given fluids intravenously through a drip, and you may need oxygen to help breathing.

In very serious cases of pneumonia, breathing assistance through a ventilator in an intensive care unit (ICU) may be required.

Aspiration pneumonia