Influenza A
Influenza A is a contagious viral respiratory illness that commonly causes abrupt fever, aches, headache, fatigue and cough.
Key takeaways
- Symptoms overlap with COVID-19 and other viruses, so testing is useful when results change treatment or precautions.
- Antiviral treatment is time-sensitive and particularly important for severe, hospitalised or higher-risk patients.
- Antibiotics do not treat influenza but may be needed for a confirmed secondary bacterial complication.
The listings below do not confirm influenza A or eligibility for antivirals; onset timing, severity, age and organ function matter.
Assessing risk and complications
Young children, older adults, pregnancy, immune suppression and chronic heart, lung or metabolic disease raise complication risk. Pneumonia can present with increasing breathlessness, recurrent fever after improvement or low oxygen. Dehydration and worsening of existing illness also require attention.
Treatment and prevention
Rest, fluids and appropriate fever relief support uncomplicated illness. Oseltamivir and other antivirals have agent-specific timing and resistance considerations; treatment should not be delayed for testing in a severely ill high-risk patient when influenza is likely. Vaccination reduces severe disease risk but does not treat current infection.
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 symptoms that sharply worsen after initial improvement.