Pneumonia is an infection that causes inflammation in one or both lungs and can range from a mild illness to a serious, potentially life-threatening condition.
The infection can be caused by bacteria, viruses, fungi and, less commonly, other organisms. The type of infection and its severity help determine the appropriate treatment.
Pneumonia affects the tiny air sacs in the lungs, known as alveoli. During an infection, these air sacs can fill with fluid or pus, making it harder for the lungs to move enough oxygen into the bloodstream.
Symptoms of pneumonia
Symptoms vary depending on the organism causing the infection and a person’s age and general health.
Common symptoms include coughing, fever or chills, fatigue, shortness of breath and chest pain that may become worse when breathing or coughing. Some people may also experience nausea, vomiting or diarrhoea.
A cough may produce mucus or phlegm. In some cases, pneumonia can cause confusion or changes in mental awareness, particularly among older adults.
Symptoms can initially resemble those of a cold or flu but may become more severe or last longer.
What causes pneumonia?
Bacteria and viruses are common causes of pneumonia. Fungi are less common but can cause the infection, particularly in people with weakened immune systems or certain underlying conditions.
Pneumonia can develop in the community or in healthcare settings. Some infections occur after a person inhales food, drink, saliva or vomit into the lungs, a condition known as aspiration pneumonia.
Healthcare providers are not always able to identify the specific germ responsible for an individual case.
Who is at greater risk?
Pneumonia can affect people of all ages, but the risk of serious illness is higher among older adults, young children and people with certain underlying health conditions.
For adults, people aged 65 and older are at increased risk. Chronic conditions affecting the heart, lungs, liver or other organs can also increase the risk, as can diabetes and a weakened immune system. Smoking is another risk factor because it damages the body’s natural defences against respiratory infections.
How pneumonia is diagnosed
A healthcare provider may begin with a medical history and physical examination, including listening to the lungs with a stethoscope.
Depending on the symptoms and suspected cause, testing may include blood tests, a chest X-ray, measurement of blood oxygen levels and analysis of sputum. More detailed tests, including a CT scan, may be used in some cases.
A chest X-ray can help confirm pneumonia and show the extent and location of inflammation, although it cannot by itself identify the organism causing the infection.
How pneumonia is treated
Treatment depends on the cause and severity of the illness, as well as the person’s age and overall health.
Bacterial pneumonia is treated with antibiotics. However, antibiotics do not treat viral pneumonia, and treatment for other forms of pneumonia depends on the organism involved. Many people with community-acquired pneumonia can be treated at home with medication, while people with severe illness may require hospital care.
Hospital treatment may be necessary when pneumonia causes serious breathing problems, low blood oxygen or other complications. Some patients may require oxygen or mechanical assistance with breathing.
Rest, adequate fluids and taking prescribed medicines as directed can support recovery. Recovery time varies, and tiredness can continue after other symptoms have improved.
Preventing pneumonia
Some cases of pneumonia can be prevented through vaccination and measures that reduce the spread of respiratory infections.
Vaccines are available against some of the bacteria and viruses that can cause pneumonia, including pneumococcal disease, influenza and COVID-19. Vaccination recommendations vary according to age, health status and other risk factors.
Regular handwashing, covering coughs and sneezes, avoiding close contact with people who are sick and staying away from others when ill can also reduce the spread of respiratory infections.
Avoiding cigarette smoke and quitting smoking can further reduce the risk, while properly managing chronic conditions such as asthma can help protect against complications.
Anyone experiencing significant breathing difficulty, persistent or worsening symptoms, or other concerning signs should seek medical assessment rather than attempting to determine the cause or treatment alone.
