What is pneumonia? Causes, signs, symptoms, risks and prevention

Pneumonia is swelling and inflammation in your lungs that’s usually caused by an infection.

You have tiny air sacs in your lungs called alveoli. When you have pneumonia, these tiny air sacs swell up and fill with liquid. This makes it harder for you to breathe. 

Is pneumonia the same as a chest infection?  

Pneumonia is a type of chest infection.  

Chest infection is a general term used to describe an infection in your lungs or airways. 

The main types of chest infections are pneumonia and bronchitis. 

Most people feel better in 2 to 4 weeks with treatment, but pneumonia can cause serious health problems. Around 29,000 people die from pneumonia each year in the UK.

We know that getting pneumonia can be scary. We have more support for people with pneumonia, including: 

• contact our helpline to talk through any worries or concerns you have
• read our advice about how pneumonia is diagnosed and treated, as well as help to recover from pneumonia.

The main causes of pneumonia are bacteria and viruses.

Bacterial pneumonia 

When bacterial infections cause pneumonia it’s called bacterial pneumonia.     

There are different bacterial infections that can cause pneumonia, but it’s usually caused by a bacterial infection called pneumococcal. 

Most people with lung conditions can get a free vaccine to help prevent pneumococcal infections.  

Viral pneumonia 

Viral pneumonia is caused by respiratory viruses like flu and RSV (respiratory syncytial virus).  

COVID-19 pneumonia is a type of viral pneumonia caused by COVID-19. 

Where can you get pneumonia?

In the community 

Most pneumonia starts outside of hospital, in the community. This is called community-acquired pneumonia.

In every 1,000 adults, 5 to 10 get pneumonia in the community each year. 

In the hospital

Pneumonia can start while you’re in hospital for something else. This is called hospital-acquired hospital.

For every 1,000 adults that are admitted to hospital, 5 to 20 get hospital-acquired pneumonia.    

Other causes and types of pneumonia 

Atypical pneumonia (walking pneumonia)

Atypical pneumonia is a type of bacterial pneumonia.  It’s called atypical because it’s caused by bacteria that is different to the bacteria that usually causes pneumonia. For example, Legionnaires’ disease is a type of atypical pneumonia. 

Atypical pneumonia is sometimes called walking pneumonia.    

Fungal pneumonia 

Pneumonia can be caused by fungal infections. This is rare in the UK and is more likely to affect you if you have a weakened immune system. 

Aspiration pneumonia 

Aspiration means accidentally breathing food or drink into your airways instead of swallowing it. This can damage your lungs and cause pneumonia.

Pneumonia symptoms can start suddenly or come on over a few days.  

Common signs and symptoms of pneumonia include: 

• coughing, you might cough up yellow or green phlegm
• breathlessness
• a high temperature (fever)
• chest pain
• feeling achy
• feeling very tired (fatigue)
• loss of appetite
• wheezing
• feeling confused, this is more common in older people. 

Is it pneumonia, an asthma attack or a lung condition flare-up?

Some pneumonia symptoms are similar to asthma, COPD, bronchiectasis, or pulmonary fibrosis symptoms. You can also have pneumonia at the same time as an asthma attack or flare-up. Sometimes pneumonia can trigger asthma attacks or flare-ups.

If you feel unwell, contact a healthcare professional and follow the advice on your asthma action plan or lung condition self-management plan.

Pneumonia can be more serious if you have a lung condition. It’s important to get treatment quickly.

Pneumonia is not contagious, but it’s usually caused by bacteria and viruses that are contagious. For example, you cannot spread pneumonia, but you can spread things that cause pneumonia, like flu. 

Anybody can get pneumonia, but some things can increase your chances of getting pneumonia and getting more ill from pneumonia.  

Who is most at risk of getting pneumonia in the community? 

You’re more at risk of getting pneumonia outside of hospital if you:

• have a lung condition like asthma, chronic obstructive pulmonary disease (COPD), bronchiectasis or pulmonary fibrosis
• are over 65 years old   
• have a learning disability  
• have a weaker immune system
• have lower air quality in your home
• smoke (if you smoke, we have support to help you stop)  
• are not eating a nutritious diet (this is called malnutrition)
• have liver disease from drinking too much alcohol.   

Babies and children under 5 are also more at risk from pneumonia. We have specific advice for pneumonia in children. 

Who is most at risk of getting pneumonia in hospital? 

You’re more likely to get pneumonia in hospital if you: 

• are being treated in a specialist hospital ward called intensive care
• have recently had surgery
• are older than 75 years old
• have got a weakened immune system
• have been in hospital for a long time.

Get vaccinated

Getting the pneumococcal (pneumonia) vaccine can help protect you against the type of bacterial infection that can cause pneumonia. This infection is caused by bacteria called Streptococcus pneumoniae. Many people with lung conditions can get this vaccine for free.   

You can also reduce your risk of getting viral pneumonia by getting the flu vaccine, RSV vaccine and COVID-19 vaccine. 

Below, we answer some questions that you might have about the pneumococcal vaccine if you have a lung condition. 

If you want more advice about the pneumococcal vaccine, the NHS has information about: 

• how often you need to get the pneumococcal vaccine 
• people who can get a free pneumococcal vaccine
• what’s in the pneumococcal vaccine
• how to get the pneumococcal vaccine 
• how the pneumococcal vaccine works. 

Can I get a free pneumococcal vaccine if I have asthma or another lung condition?

You can get a free pneumococcal vaccine if you have:  

• asthma, if you need constant or repeated use of steroids tablets to manage your asthma
• bronchiectasis
• bronchopulmonary dysplasia
• chronic obstructive pulmonary disease (COPD), including chronic bronchitis and emphysema
• cystic fibrosis 
• interstitial lung disease, including pulmonary fibrosis, pneumoconiosis and sarcoidosis. 

Are the pneumococcal vaccine side effects different for people with asthma or another lung condition?

The most common side effects of the pneumococcal vaccine are: 

• swelling or pain where you got your injection
• a high temperature (fever)
• feeling tired
• loss of appetite. 

There is no evidence that people with asthma or another lung condition will get different side effects to anybody else that gets that pneumococcal vaccine. 

If you get any side effects that you’re worried about, speak to your GP, nurse or pharmacist. You can also register any side effects using the MHRA’s (Medicines and Healthcare Products Regulatory Agency) Yellow Card scheme.