Overview
Flu is a contagious respiratory illness caused by influenza viruses. It usually comes on quickly and can make you feel much more unwell than a common cold. Most people recover at home, but some are at higher risk of serious complications.
How common is it?
Flu is common in winter and causes yearly outbreaks. Some seasons are milder than others, but flu can lead to serious illness and hospital admission.
Causes and risk factors
Flu spreads through coughs, sneezes, hands, and surfaces contaminated with the virus. People can pass it on before they realize how unwell they are.
Common risk factors
- Age 65 or over
- Pregnancy
- Diabetes
- Heart, lung, kidney, liver, brain, or nerve conditions
- A weakened immune system
- Young children
Symptoms
- A sudden high temperature or feeling feverish
- An aching body
- Feeling very tired or exhausted
- A dry cough
- A sore throat
- A headache
- A runny or stuffy nose
- Sometimes vomiting or diarrhoea, especially in children
When to see a doctor
Seek urgent medical advice if you have flu symptoms and feel short of breath, have chest pain, confusion, are coughing up blood, or are getting worse rather than better. Contact a clinician early if you are at higher risk of complications, because antiviral treatment works best when started soon after symptoms begin.
Diagnosis
Flu is often diagnosed from symptoms during flu season. Testing may be used in hospital, for people at higher risk, or when the result could change treatment decisions.
Treatments
Rest, fluids, and pain relief
Rest, drink fluids, and use paracetamol or ibuprofen if they are suitable for fever, headache, and muscle aches.
Antiviral medicines for selected people
Antiviral treatment may be recommended for people at higher risk of serious flu or who are very unwell. It works best when started early.
Hospital care for severe flu
People with severe breathing problems, dehydration, or complications such as pneumonia may need hospital treatment.
Self-care and lifestyle
- Stay home and avoid close contact with other people while you have a high temperature or feel too unwell for normal activities
- Wash hands often and cover coughs and sneezes
- Do not take extra cold and flu remedies that duplicate paracetamol
- Do not give aspirin to children under 16
Prevention
The flu vaccine is the best protection for eligible adults and children. Hand hygiene and covering coughs and sneezes also help reduce spread.
Sources and review
Last reviewed: 20 July 2026 by Living Diabetes Editorial Team. This guide was checked against current patient and professional guidance. It is educational and does not replace care from your own healthcare team.