Viral infection causing respiratory illness. Review possible symptoms, contributing factors, assessment, warning signs and care options.
About Influenza (Flu)
Viral infection causing respiratory illness
Influenza is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs.
It can cause mild to severe illness and can lead to hospitalization or death in high-risk groups.
Editorial update (28 September 2026): structured medical content awaits clinical reviewer sign-off.
How assessment may be approached
Assessment may include symptom timing, fever, exposures, travel, contacts, vaccination status and medicines. Tests may identify a specific infection, but treatment decisions should match clinical urgency and local guidance.
Care can range from monitoring and fluids to prescribed treatment, infection-control measures and follow-up. Ask whether antibiotics or other medicine are actually indicated and how to prevent spread.
When to seek prompt care
Seek urgent care for stiff neck, severe headache, confusion, breathing difficulty, persistent vomiting, dehydration, rash with fever, severe weakness or rapidly worsening illness.
Symptoms
- Fever
- Body aches
- Chills
- Fatigue
- Cough
- Sore throat
Possible causes
- Influenza viruses (A, B, C)
- Airborne transmission
- Surface contact
Care and treatment options
- Rest and fluids
- Antiviral medications
- Fever reducers
- Symptom relief
- Annual vaccination
Key points
- Causes 3-5 million severe cases yearly
- Vaccine available annually
- Most recover within 2 weeks
- Can be serious in elderly
Preparing for a consultation
- Fever readings and timing of symptoms.
- Travel, food, water, animal or contact exposures.
- Vaccination history and immune-suppressing medicines.
- Recent test results, medicines and who else may be unwell.
Questions worth asking
- Is Influenza (Flu) the most likely explanation for these symptoms, and what alternatives should be checked?
- Which symptoms or findings would require urgent review?
- Are medicines, underlying health problems or lifestyle factors contributing?
- What tests or examinations are needed now, and what can safely wait?
- What treatment or self-care options are reasonable, and when should I be reviewed again?
- What is the expected benefit, limit, cost and follow-up plan for the suggested care?
Related conditions
Related clinicians
Medical information limitations
This page summarizes listed condition information and cannot confirm a diagnosis or choose treatment. Do not start, stop or change prescribed treatment based only on this page.
Common questions
What is Influenza (Flu)?
Viral infection causing respiratory illness This is general information; the name describes a possible diagnosis or clinical problem, not a personal diagnosis.
How might a clinician assess Influenza (Flu)?
Assessment may include symptom timing, fever, exposures, travel, contacts, vaccination status and medicines. Tests may identify a specific infection, but treatment decisions should match clinical urgency and local guidance.
What care may be discussed?
Care options listed include Rest and fluids, Antiviral medications, Fever reducers, Symptom relief. Which option is appropriate depends on the confirmed cause, severity, preferences and contraindications.
When should Influenza (Flu) be checked urgently?
Seek urgent care for stiff neck, severe headache, confusion, breathing difficulty, persistent vomiting, dehydration, rash with fever, severe weakness or rapidly worsening illness.
How should I prepare for a consultation?
Fever readings and timing of symptoms. Travel, food, water, animal or contact exposures. Vaccination history and immune-suppressing medicines. Recent test results, medicines and who else may be unwell. Bring previous reports and a current medicine list where relevant.
Can this page diagnose or treat the condition?
No. A page about Influenza (Flu) can help you understand possible features and questions, but it cannot confirm a diagnosis or choose treatment. A qualified clinician should assess your symptoms, history and any test results.
General information only; it is not a diagnosis or a substitute for a qualified clinician’s advice.