Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli.[3][14] Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing.[15] The severity of the condition is variable.[15]

Other namesPneumonitis
Chest X-ray of a pneumonia caused by influenza and Haemophilus influenzae, with patchy consolidations, mainly in the right upper lobe (arrow)
SpecialtyPulmonology, Infectious disease
SymptomsCough, shortness of breath, chest pain, fever[1]
DurationFew weeks[2]
CausesBacteria, virus, aspiration[3][4]
Risk factorsCystic fibrosis, COPD, sickle cell disease, asthma, diabetes, heart failure, history of smoking, very young age, older age[5][6][7]
Diagnostic methodBased on symptoms, chest X-ray[8]
Differential diagnosisCOPD, asthma, pulmonary edema, pulmonary embolism[9]
PreventionVaccines, handwashing, not smoking[10]
MedicationAntibiotics, antivirals, oxygen therapy[11][12]
Frequency450 million (7%) per year[12][13]
DeathsFour million per year[12][13]

Pneumonia is usually caused by infection with viruses or bacteria, and less commonly by other microorganisms.[lower-alpha 1] Identifying the responsible pathogen can be difficult. Diagnosis is often based on symptoms and physical examination.[8] Chest X-rays, blood tests, and culture of the sputum may help confirm the diagnosis.[8] The disease may be classified by where it was acquired, such as community- or hospital-acquired or healthcare-associated pneumonia.[18]

Risk factors for pneumonia include cystic fibrosis, chronic obstructive pulmonary disease (COPD), sickle cell disease, asthma, diabetes, heart failure, a history of smoking, a poor ability to cough (such as following a stroke), and a weak immune system.[5][7]

Vaccines to prevent certain types of pneumonia (such as those caused by Streptococcus pneumoniae bacteria, linked to influenza, or linked to COVID-19) are available.[10] Other methods of prevention include hand washing to prevent infection, not smoking, and social distancing.[10]

Treatment depends on the underlying cause.[19] Pneumonia believed to be due to bacteria is treated with antibiotics.[11] If the pneumonia is severe, the affected person is generally hospitalized.[19] Oxygen therapy may be used if oxygen levels are low.[11]

Each year, pneumonia affects about 450 million people globally (7% of the population) and results in about 4 million deaths.[12][13] With the introduction of antibiotics and vaccines in the 20th century, survival has greatly improved.[12] Nevertheless, pneumonia remains a leading cause of death in developing countries, and also among the very old, the very young, and the chronically ill.[12][20] Pneumonia often shortens the period of suffering among those already close to death and has thus been called "the old man's friend".[21]

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This article uses material from the Wikipedia article Pneumonia, and is written by contributors. Text is available under a CC BY-SA 4.0 International License; additional terms may apply. Images, videos and audio are available under their respective licenses.