Pneumonia is swelling or inflammation of tissue in the lungs.
Around 8 in 1,000 people in the UK get pneumonia each year, with cases more common during autumn and winter.
People in any age group can develop pneumonia, but it is more serious for certain people, for example, elderly people and young children.
Pneumonia is usually caused by bacteria, most often Streptococcus pneumoniae.
Viruses can also cause it, including flu viruses and respiratory syncytial virus (RSV).
Less commonly, pneumonia can be caused by breathing something into the lungs, such as food or chemicals, called aspiration pneumonia.
Fungal infections can cause fungal pneumonia, but this is rare in the UK.
Some people get pneumonia in hospital when having an operation or using breathing tubes. When this happens it is called hospital-acquired pneumonia.
Pneumonia can also develop in the lungs after an infection spreads from somewhere else in the body.
Is pneumonia contagious?
Pneumonia isn't contagious, but the bacteria or viruses that cause it can be caught by breathing in droplets from coughs and sneezes from an infected person.
Pneumonia may come on quickly over 24-48 hours, or symptoms may develop over several days.
Symptoms of pneumonia commonly include:
- Dry cough
- Cough with thick yellow, green or brown phlegm
- Blood in phlegm
- Breathing difficulty, breathlessness
- Rapid breathing
- Shallow breathing
- Faster heartbeat
- Generally unwell
- No appetite
- Chest pain, especially when coughing.
Symptoms that are seen less commonly include:
Seek medical advice if you have pneumonia symptoms.
Who is at risk of pneumonia?
Getting pneumonia is more likely for:
A doctor will diagnose pneumonia based on the symptoms, the person's medical history, and by performing a physical examination that includes taking their temperature, examining the chest and listening with a stethoscope for rattling or crackling noises whilst they breathe.
Other conditions with similar symptoms will need to be ruled out, such as colds and flu.
Other tests may be arranged, including a chest X-ray or laboratory test of a phlegm sample.
Follow-up appointments may be needed if symptoms don't improve.