Which organism causes pneumonia?

Bacterial pneumonia and viral pneumonia can produce overlapping symptoms, including cough, fever, chills and phlegm. COVID-19 and influenza are examples of viral illnesses that can affect the lungs. The likely cause is considered from the pattern of illness, recent contacts, travel or healthcare exposure, other conditions and examination findings. A swab, blood test or sample of phlegm may sometimes help, but a negative or unavailable test does not by itself explain every symptom.

Take medicines only as prescribed and do not use leftover antibiotics for a new illness. Rest, drink fluids if safe, avoid smoking and reduce close contact with people who are vulnerable while you are unwell. Tell the clinician about recent antibiotics, immune problems, travel, animal exposure and any known contact with influenza or COVID-19, because these details can change the assessment.

Get urgent medical help for severe breathlessness, blue or grey lips, confusion, fainting, severe chest pain, inability to drink or rapidly worsening weakness. These features can reflect serious lung illness or sepsis and need prompt assessment, whatever the suspected organism.

Ask which causes are being considered, whether testing would change treatment, and how to take or monitor the prescribed medicine. Ask when to return if cough, fever, chills or phlegm continue.