Which viruses can cause pneumonia?

Viruses can inflame the air sacs and airways, making oxygen transfer less efficient. Fever, chills, cough, phlegm, muscle aches and breathlessness may occur, but the pattern varies. Influenza and COVID-19 are recognised viral causes; other respiratory viruses can also affect the lungs. A viral infection can sometimes be followed by a bacterial infection, so a change after initial improvement deserves review. A positive test for a virus does not by itself show how severely the lungs are affected.

Seek medical advice if you have breathing difficulty, chest pain, persistent fever, or symptoms that are worsening rather than settling. A clinician can check your breathing and oxygen level and decide whether testing or a chest image is appropriate. Some antiviral medicines work best when started early and are suitable only for particular infections or people. Do not start antibiotics without advice, because they do not treat viruses. Rest, fluids and avoiding smoke support recovery.

Call emergency services for severe breathlessness, blue or grey lips, confusion, collapse, or inability to remain awake. Arrange urgent review if breathing becomes harder, fever returns after improving, chest pain intensifies, or you cough blood. Severe viral illness can strain the lungs and other organs and may lead to sepsis.

Ask whether viral testing is useful, whether antiviral treatment fits your situation, how to monitor breathing at home, and which changes require immediate help.