Pneumonia is an infection of your lungs. It is usually caused by bacteria or a virus, and is often triggered by a cold or the flu.

Key points

  1. Anyone can develop pneumonia, but young children and older adults are often worst affected.
  2. See your doctor or call Healthline on 0800 611 116 if you notice signs of a more serious chest infection, such as shortness of breath and high fever, or if you feel very unwell.
  3. Most cases of pneumonia can be treated at home with rest, plenty of fluids and antibiotics.
  4. Young children, older adults or those with severe pneumonia may need to stay in hospital for treatment.

What is pneumonia?

Pneumonia is an infection that causes inflammation of the air sacs in one or both lungs. It happens when your body’s immune system is overwhelmed, such as during a cold or a bout of the flu, and can’t fight off the bug causing the infection. When infection sets in, the air sacs in one or both lungs fill with pus and fluids, making breathing difficult.

What causes pneumonia?

Pneumonia is usually caused by a bacterial or viral infection.

Pneumonia in adults is usually the result of a pneumococcal infection, caused by bacteria called Streptococcus pneumoniae. Many other types of bacteria, including Haemophilus influenzae and Staphylococcus aureus, can also cause pneumonia. 

Viruses, such as respiratory syncytial virus (RSV) and the flu virus, are a common cause of pneumonia in children.

It can be difficult to tell whether the pneumonia is due to a virus or bacteria.

Pneumonia can also be caused by fungal infections but this is relatively uncommon.

Who is at risk?

Anyone can develop pneumonia but the risk is greater in babies and children aged 4 years and under and adults older than 65 years. Other risk factors include:

  • recently having had a cold or the flu
  • having a chronic lung condition
  • having a weakened immune system
  • drinking excessive alcohol or smoking
  • being a patient in hospital.

In children, the risk of pneumonia is increased by:

  • premature birth
  • poor nutrition
  • low birth weight
  • not being breastfed
  • exposure to tobacco smoke
  • lack of insulation and heating at home
  • living in damp, mouldy and/or overcrowded conditions.

What are the 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:

  • cough (often with yellow or green coloured phlegm)
  • fever, which may be mild or high
  • shaking chills
  • shortness of breath
  • increased effort required to take a breath
  • low energy and fatigue
  • loss of appetite
  • headache
  • chest pain that gets worse when you breathe deeply or cough.

When to seek medical help

See your doctor if you have an ongoing chest infection that is not getting better.

Seek medical assistance straight away if:

  • your child develops a chest infection after a cold or the flu – children can become very sick very quickly if they develop pneumonia
  • you are experiencing severe symptoms, such as rapid breathing, chest pain or confusion, or if a bluish tinge develops in your skin, lips and nail beds.

How is pneumonia diagnosed?

To diagnose pneumonia your doctor will take a medical history and do a physical exam. Pneumonia may be suspected if they hear coarse breathing, wheezing or crackling sounds when listening to your chest through a stethoscope.

A chest x-ray is not usually necessary but may be used to help diagnosis in some cases.

What is the treatment for pneumonia?

Mild cases of pneumonia can be treated at home with rest, antibiotics and drinking plenty of fluids. However, hospital admission is often recommended for babies, young children and older adults, or for those who have severe pneumonia.

Antibiotics can be used to treat pneumonia caused by bacteria but are not effective if it is caused by a virus. However, it is difficult to tell if pneumonia is caused by bacteria or a virus, so antibiotics are normally prescribed if pneumonia is diagnosed.

Treatment at home

If treatment at home is advised, you will normally need to visit your doctor for a medical review at least once a day at first, and sometimes in the morning and afternoon until you are clearly getting better. This includes weekends, so you may have to attend an after-hours clinic.

To help your recovery:

  • rest as much as possible – in an upright position is best
  • drink plenty of fluids, mainly water
  • take antibiotics as prescribed
  • avoid smoking or passive smoking
  • take medications (such as paracetamol or ibuprofen) if required for relief of pain and fever.

If possible, have someone stay with you or check in on you while you are unwell. Make sure you have access to a phone and are able to contact your doctor or emergency services if required. 

Treatment in hospital

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

How long will it take to recover from pneumonia?

Once you have started treatment, your symptoms should improve steadily. How quickly they improve will depend on how severe your pneumonia is. As a general guide, after:

  • one week – your fever should have gone
  • four weeks – your chest pain and mucus production should have reduced a lot
  • six weeks – your cough and breathlessness should have reduced a lot
  • three months – most symptoms should have gone, but you may still feel very tired (fatigue)
  • six months – most people will feel back to normal.

How can I avoid getting pneumonia?

To help prevent pneumonia:

  • get the seasonal flu vaccination– it can help prevent pneumonia caused by the flu virus
  • get a pneumonia vaccination – this vaccine is especially recommended for anyone at high risk of pneumococcal pneumonia
  • wash your hands often or use an alcohol-based hand sanitiser
  • don't smoke – smoking damages your lung's ability to fight infection
  • stay rested and fit
  • stay home when you're sick
  • avoid people who have a cold or the flu.

Pneumonia vaccination

Three vaccines are available in New Zealand to prevent some forms of pneumonia:

  • All children should receive the pneumococcal vaccine Synflorix as part of the New Zealand Immunisation Schedule.
  • Another vaccine is used for children at high risk of complications (funded for children aged under 5 years).
  • For all other high-risk people, vaccination is recommended, but not funded.

Learn more

Pneumonia – an overview NHS Choices, UK
Mayo Clinic, Mayo Foundation for Medical Education and Research, 2013
Pneumonia Kids Health NZ, Paediatric Society of New Zealand and Starship Foundation, 2014
Pneumonia – parent/caregiver informationCanterbury District Health Board, 2012 

Credits: Health Navigator Editorial Team.