What should you know about Spanish influenza 1918?

The name refers to the influenza pandemic that began during the final period of the First World War. It was caused by an influenza virus, not by a uniquely Spanish illness; the label became common partly because reports from Spain were less restricted by wartime censorship. People could develop fever, chills, headache, cough, marked fatigue, and a general feeling of being unwell. Some infections progressed to inflammation or infection in the lungs, including [Pneumonia](/conditions/pneumonia/). This historical event is different from ordinary seasonal [Influenza](/conditions/influenza/), although both are influenza illnesses.

If you have a current fever, [Cough](/symptoms/cough/), chills, or unusual tiredness, rest, drink fluids if you can, and limit close contact while you feel unwell. Note when symptoms began and whether breathing is becoming harder. A clinician can assess present-day influenza and other causes; the historical label does not diagnose a current illness. Seek advice sooner if you are pregnant, older, immunocompromised, or managing a long-term heart or lung condition.

Get urgent medical help for severe breathlessness, bluish or grey lips, confusion, fainting, chest pain, inability to keep fluids down, or a clear deterioration after initial improvement. A persistent high fever, worsening cough, or profound weakness also deserves prompt clinical assessment, because influenza can be followed by pneumonia. For milder illness, arrange medical advice if symptoms are not settling or you are worried.

Ask whether your symptoms fit current influenza or another infection, whether you need an examination, and which warning signs should prompt urgent help. You can also ask how to protect household members and when it is reasonable to return to work, school, or normal activities.