Influenza
Influenza is a contagious infection caused by influenza viruses, often beginning suddenly with fever, muscle aches, headache, fatigue and cough.
Key takeaways
- Influenza cannot always be distinguished from COVID-19 or other respiratory infections by symptoms alone.
- Most healthy people recover with supportive care, while antiviral treatment is prioritised for severe illness and higher-risk groups.
- Worsening breathlessness or fever returning after improvement may signal pneumonia or another complication.
The listings below do not establish influenza or safe treatment; onset, testing, age, pregnancy and comorbidities affect decisions.
Who needs closer assessment
Pregnancy, very young or older age, immune suppression and chronic heart, lung, kidney or metabolic disease increase risk. Pulse oximetry, hydration and breathing effort help determine severity. Testing can inform antiviral and infection-control decisions, especially when several viruses are circulating.
Supportive and antiviral roles
Fluids, rest and appropriate fever relief are adequate for many uncomplicated cases. Neuraminidase inhibitors have greatest benefit when started early but may still be used later in severe or hospitalised illness. Antibiotics are reserved for bacterial co-infection rather than coloured sputum alone.
When to seek urgent care
Seek emergency care for severe breathlessness, blue or grey lips, confusion, fainting, persistent chest pain, inability to keep fluids down or rapid deterioration.
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