Overview - Pneumonia

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

There are clusters of tiny air sacs at the end of the breathing tubes in your lungs. If you have pneumonia, these tiny sacs become inflamed and fill up with fluid.

Symptoms of pneumonia

Symptoms 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
  • fever
  • 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
  • nausea or vomiting
  • wheezing
  • joint and muscle pain
  • feeling confused and disorientated, particularly in elderly people

When to see your GP

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

Urgent advice: Get urgent medical attention if:

  • you have severe symptoms such as rapid breathing, chest pain or confusion

Pneumonia affects around 8 in 1,000 adults each year. It's more widespread in autumn and winter.

Pneumonia can affect people of any age. 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 may need hospital treatment if they develop pneumonia.

Causes of pneumonia

Pneumonia is usually the result of a pneumococcal infection. It is caused by bacteria called Streptococcus pneumoniae.

Different types of bacteria and viruses can also cause pneumonia.

As well as bacterial pneumonia, other types include:

Viral pneumonia
This is mostly caused by the respiratory syncytial virus (RSV). Viruses are a common cause of pneumonia in young children.

Almost all serious complications of COVID-19 feature pneumonia.

Aspiration pneumonia
This is caused by breathing in vomit, a foreign object, such as a peanut, or a harmful substance, such as smoke.

Fungal pneumonia
This is rare in Ireland and more likely to affect people with a weakened immune system.

Hospital-acquired pneumonia
This develops while being treated in hospital for another condition or having an operation. People on breathing machines are particularly at risk of developing ventilator-associated pneumonia.

At-risk groups

The following groups have an increased risk of developing pneumonia:

  • babies and very young children
  • elderly people
  • people who smoke
  • people with asthma, cystic fibrosis, or a heart, kidney or liver condition
  • people with a weakened immune system – for example, as a result of chemotherapy or a recent illness such as flu or HIV

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. This is because it shares symptoms with conditions, such as the common cold and asthma.

To help make a diagnosis, your 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

Your GP may also take your temperature. They will 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 healthy lungs.

If you have mild pneumonia, you probably won't need to have a chest x-ray or any other tests.

Treating pneumonia

Mild pneumonia can usually be treated at home by:

  • getting plenty of rest
  • taking antibiotics
  • drinking plenty of fluids

If you don't have any other health problems, you should respond well to treatment and soon recover. Your cough may last for some time.

It’s usually safe for someone with pneumonia to be around others. But if you have a weakened immune system, you are less able to fight off infections. you should 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. In some cases these can be fatal, depending on a person's health and age.

Read more about treating pneumonia

Complications of pneumonia

Complications of pneumonia are more common in:

  • young children
  • older people
  • those with pre-existing health conditions, such as diabetes

Possible complications of pneumonia include:

  • pleurisy – where the thin linings between your lungs and rib cage (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 any of these complications.

Preventing pneumonia

Most cases of pneumonia are bacterial and are not passed on from one person to another. But good standards of hygiene will help prevent germs spreading.

You should:

  • cover your mouth and nose with a tissue when you cough or sneeze
  • throw away used tissues immediately
  • wash your hands regularly to avoid spreading germs to other people or objects

A healthy lifestyle can also help prevent pneumonia.

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. These will make you more vulnerable to pneumonia.

Read more about how alcohol affects the body

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

Content supplied by the NHS and adapted for Ireland by the HSE

Page last reviewed: 6 April 2020
Next review due: 6 April 2023

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.