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What is Pneumonia?

Last updated on 25th April 2023

During the first eight months of 2020, England and Wales saw 13,619 people die from pneumonia. To compare, there were 394 deaths attributed to influenza during this time, and 48,168 attributed to COVID-19. According to the Office for National Statistics, there were 19,642 deaths attributed to pneumonia in 2020 in the United Kingdom as a whole for the entire year. It is thought that between one and three adults in every thousand (0.1% to 0.3%) have pneumonia at any one time.

What is pneumonia?

Pneumonia is an infection of the lungs. Like many infections, it can be mild or severe. Mild cases of pneumonia can be treated at home, while severe cases require hospital admission.

Pneumonia happens when the alveoli (your lungs’ air sacs) fill with pus or fluid. This makes it difficult to breathe and take in adequate amounts of oxygen into your bloodstream.

Anyone can get pneumonia, but it is more prevalent in people aged over 65 or younger than two. This is because these age groups tend to have weaker immune systems and aren’t as strong to be able to fight off the illness.

Pneumonia can affect one or both lungs. It’s also possible to have the condition and not know about it. This is what doctors refer to as ‘walking pneumonia’.

Pneumonia has many causes. It is contagious only if it has resulted from a virus or bacterial infection.

Doctor showing man with pneumonia x-ray of his lungs

Signs and symptoms of pneumonia

As mentioned above, there might be no signs of pneumonia at all (walking pneumonia). Most of the time, though, there are symptoms, and these can develop quite suddenly over a period of 24 or 48 hours. They can also present more slowly and appear over a few days.

Common pneumonia symptoms include:

  • A cough – This could be a wet or dry cough. If it’s a wet cough, it might produce thick green, yellow, blood-stained or brown phlegm (mucus).
  • Difficulty breathing – The breath might be shallow and rapid. People with pneumonia often feel breathless, even when they’re at rest.
  • A rapid heartbeat.
  • A high temperature.
  • Generally feeling unwell.
  • Shivering and sweating.
  • Loss of appetite.
  • Chest pain – This tends to get worse when coughing and even when just breathing.

Less common pneumonia symptoms include:

  • Fatigue.
  • Headaches.
  • Haemoptysis (coughing up blood).
  • Nausea and vomiting.
  • Wheezing.
  • Muscle and joint pain.
  • Being disorientated or feeling confused (more common in the elderly).

Early signs of pneumonia also look like many other conditions like colds, flu and coronavirus, so it can be hard to detect. Typically, though, pneumonia symptoms will get worse after a day or two.

Pneumonia symptoms in infants and children

When children develop pneumonia, the symptoms are often more difficult to spot.

Children might have:

  • Trouble breathing.
  • Rapid breathing.
  • A cough.
  • A fever.
  • Wheezing.
  • Cyanosis (blue lips, skin or fingertips).

Young babies might have difficulty feeding or just seem fussy and unsettled.

Cold and flu symptoms vs pneumonia

As mentioned above, the early signs of pneumonia are very similar to colds and flu. In fact, pneumonia can even be a complication of these two conditions. This is because the viruses that cause them can get into the lungs.

If you’ve had the flu or a cold, you might start feeling better but then worse again.

Cold symptoms will often start quite slowly and you’re more likely to experience a runny nose, sneezing, or a sore throat too. What’s more, colds don’t typically cause a high temperature in adults.

For flu, you tend to have symptoms that seem to come on quite quickly and you often have a headache, aches and pains, fatigue, a dry cough, and a fever above 38 °C.

These flu symptoms usually ease in two to five days, though it’s possible to have a sore throat or mild cough for up to two weeks.

What causes pneumonia?

Usually, pneumonia is caused by a bacterial infection (e.g., a chest infection) caused by Mycoplasma pneumoniae or Streptococcus pneumoniae, but there are other causes too.

Aside from bacterial pneumonia, which accounts for most cases, you can have:

  • Viral pneumonia – 15% of pneumonia cases are caused by a virus, like Covid-19, RSV, cold viruses, and influenza viruses. Respiratory Syncytial Virus (RSV) is the main cause of pneumonia in babies under one year old, and viruses are the main cause of pneumonia in pre-school children. Viral pneumonia is typically mild, but it can be severe.
  • Fungal pneumonia – This is rare in the United Kingdom and is much more likely to be a problem for people who have weaker immune systems or chronic health conditions. It is usually caused by inhaling the fungi that are found in bird droppings or soil.
  • Aspiration pneumonia – This is caused by someone breathing in a foreign object (e.g., a nut), a harmful substance like a chemical or smoke, or vomit.
  • Hospital-acquired pneumonia – This happens when someone is in hospital and having an operation or being treated for an unrelated condition. Patients who spend time on breathing machines in intensive care are at a greater risk of developing pneumonia because of their use of a ventilator. Hospital-acquired pneumonia tends to be caused by antibiotic-resistant bacteria.

When pneumonia isn’t acquired in a hospital, it is called community-acquired pneumonia. If it has been acquired in a healthcare facility, it will be referred to as healthcare-acquired pneumonia. This affects people living in care facilities long-term, or those who visit outpatient clinics like kidney dialysis centres.

Young child in hospital with doctor

Who is more at risk?

While anyone can develop pneumonia, there are some groups of people with an increased risk.

This includes:

  • Infants and young children.
  • Older people (65+).
  • Smokers – smoking damages both the lungs and the body’s natural defences against the pneumonia-causing viruses and bacteria.
  • People living with health conditions like cystic fibrosis, asthma, or kidney, liver or heart conditions.
  • People with weakened immune systems, e.g., because they’ve recently had a bout of illness like flu, or because they have an autoimmune condition, COPD (chronic obstructive pulmonary disease), have AIDS or are HIV positive, are receiving chemotherapy, or have had an organ transplant.
  • People who are hospitalised – especially if they have been in intensive care and have been on a ventilator.

When to get medical help

It’s important to see a doctor if you have chest pain, difficulty breathing, a persistent fever (39°C +) and a persistent cough – especially if there is phlegm.

If you already have a weakened immune system or a chronic health condition like those mentioned above, it’s essential to see a doctor straight away.

This is because pneumonia can become life-threatening for some people.

Pneumonia complications

Pneumonia itself is a complication of other infections. However, it can also develop into other problems. Those who are young (babies and pre-school children), older (65+), and anyone with a pre-existing condition like diabetes, is at risk of pneumonia complications.

Here are some possible pneumonia complications:

  • Lung abscesses – This is rare as far as pneumonia complications go and it’s mostly seen among those who have pre-existing medical conditions or who have misused alcohol severely.
  • Pleurisy – This is when the pleura (the lining between the ribcage and lungs) become inflamed. This can then mean respiratory failure in severe cases.
  • Pleural effusion – This is similar to pleurisy only there is a fluid build-up in the lung linings and chest cavity. This fluid can be infected too.
  • Sepsis (blood poisoning or bacteraemia) – This is a serious complication, but it is rare. In the worst cases, it can cause organ failure and death.
  • Difficulty breathing – You might need help with breathing while the lungs heal.

If you develop pneumonia complications, it’s highly likely you’ll be admitted to a hospital to be treated.

Woman having breathing difficulties due to pneumonia

Treatments and diagnosis

When pneumonia is possible or suspected, a doctor will ask the patient about their symptoms and the onset of them. They’ll also ask about medical history and lifestyle factors like whether the patient smokes and if they’ve been near sick people at home, work or school.

In terms of physical examination, they will listen to the lungs. Pneumonia is often heard as bubbling, rumbling or cracking sounds when the patient inhales. The doctor will also check the patient’s oxygen saturation using pulse oximetry to measure the oxygen levels in the blood. Anything below 92% is a cause for concern.

Patients are usually taken for a chest X-ray to confirm a diagnosis and to see how far the infection has spread. X-ray changes aren’t usually visible until 48 hours after the pneumonia symptoms began. They may also have blood tests or a sputum test to look for the infection.

If the symptoms began while the patient was in hospital or there are other health conditions present, the doctor might do more tests like a blood gas test to measure how much oxygen is in the blood in the arteries. They might also perform a bronchoscopy to check for problems like blockages in the airways. If they need a more detailed image of the lungs, they might perform a CT scan.

If complications like pleurisy or pleural effusion are suspected, they might perform a pleural fluid culture, which removes some of the fluid from the lining of the lungs to check for infection.

Pneumonia can be hard to diagnose because it shares many common features with other respiratory illnesses like colds, influenza, bronchitis, asthma and COVID-19.

Pneumonia treatments

If a patient has mild pneumonia, it will usually be treated at home. If it is likely to have been caused by a bacterial infection, antibiotics will be given. The patient should ensure they have lots of rest and drink lots of fluids. When a patient is otherwise fit and healthy, they should respond well to this treatment and will usually recover quite quickly, though the cough can linger for a while.

If the patient is in an at-risk group, pneumonia is usually more severe, and the patient might need to be admitted to the hospital for treatment. This is due to the fact that it can have serious complications, which might be life-threatening, depending on the patient’s age and health.

When the pneumonia is caused by a bacterial infection, the patient will receive antibiotics. In mild cases, this will be a course of oral antibiotics taken at home. For severe cases, it will require IV antibiotics as an inpatient.

Antibiotics don’t work for viral pneumonia. Instead, patients just need to rest, take paracetamol for their fever, and drink lots of fluids to avoid dehydration.

For severe cases, oxygen therapy might be needed to maintain oxygen levels. This would be done in an inpatient setting.

No matter the type of pneumonia, it will take a while to recover fully. It’s common to take a whole week off a daily routine and rest the entire time. Fatigue can persist for a month too.

Preventing pneumonia

In the majority of cases, pneumonia is caused by a bacterial infection elsewhere (like bronchitis or a chest infection). This means that people can pass on the bacteria through coughing and sneezing. Though others may catch the bacterial infection, it doesn’t mean they will develop pneumonia. Regardless, it’s important to practise good hygiene to prevent bacteria from spreading.

Anyone with a respiratory illness should:

  • Cover their nose and mouth with a tissue or handkerchief with every sneeze or cough.
  • Put all used tissues in the bin straight away – bacteria can stay alive for several hours after leaving the mouth or nose.
  • Wash hands frequently to avoid passing infections to others.

Leading a healthy lifestyle is also a way of preventing pneumonia. Smoking, for example, damages the lungs and increases a person’s risk of infection. Using alcohol, particularly with prolonged and excessive use, is known to weaken the natural defences in the lungs and makes people more susceptible to developing pneumonia.

Anyone with an elevated risk of developing pneumonia should receive the flu vaccine and the pneumococcal vaccine to try to prevent an infection.

Washing hands to stop spread of germs

Summing up

Pneumonia is more widespread in the cooler months of autumn and winter. It can affect people of any age but is more common (as well as more serious) in older people and babies/young children. People in these groups are much more likely to need to go to hospital for treatment.

Most pneumonia has a bacterial cause but there are other causes too, including viruses. Thankfully, most people recover well from this illness, though recovery does take time. It can, however, be life-threatening, particularly for those in more vulnerable groups.

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About the author

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Louise Woffindin

Louise is a writer and translator from Sheffield. Before turning to writing, she worked as a secondary school language teacher. Outside of work, she is a keen runner and also enjoys reading and walking her dog Chaos.