Explainer
How long is flu contagious? Symptoms, recovery and when to stay at home
Flu is most infectious in the first few days. This guide sets out the symptoms, how long you are likely to be infectious and when to get help, drawing on NHS and UKHSA guidance.
Not medical advice. This article summarises public NHS and UKHSA information. If you are worried about your health or someone else's, use NHS 111 online or call 111. In an emergency call 999.
How long are you infectious?
The NHS says flu is very infectious and that you are more likely to pass it on in the first five days after you are infected. Flu spreads through germs from coughs and sneezes, which can live on hands and surfaces for 24 hours.
UKHSA's guidance for people with symptoms of a respiratory infection is to try to stay at home and avoid contact with other people if you have a high temperature or do not feel well enough to go to work or carry out normal activities. You can return to normal activities when you no longer have a high temperature (if you had one) or no longer feel unwell. UKHSA notes that a cough or tiredness can carry on after other symptoms have improved, and that this does not mean you are still infectious.
Symptoms of flu
Flu symptoms come on very quickly. According to the NHS they can include:
- a sudden high temperature
- an aching body
- feeling tired or exhausted
- a dry cough
- a sore throat
- a headache
- difficulty sleeping
- loss of appetite
Children have similar symptoms but can also have ear pain, sore eyes and swollen glands, and may seem less active.
Is it flu or a cold?
| Flu | Cold |
|---|---|
| Appears quickly, within a few hours | Appears gradually over one to two days |
| Affects more than just your nose and throat | Affects mainly your nose and throat |
| Makes you feel exhausted and too unwell to carry on as normal | Makes you feel unwell, but well enough to do normal activities |
Source: NHS. UKHSA points out that the symptoms of flu, COVID-19 and other respiratory infections are very similar and cannot be told apart reliably from symptoms alone.
Looking after yourself
The NHS advises resting, drinking plenty of water and taking paracetamol or ibuprofen to bring down a temperature and ease aches. A pharmacist can recommend remedies. Do not take paracetamol at the same time as flu remedies that also contain paracetamol, and do not give aspirin to children under 16. Antibiotics do not work against flu because it is a virus.
When to get help
The NHS advises asking for an urgent GP appointment or using NHS 111 if you have flu symptoms and you are 65 or over, pregnant or recently gave birth, have a long-term condition or weakened immune system, feel very unwell or short of breath, or your symptoms have not improved after 7 days. It also applies if you are worried about a baby's or child's symptoms.
Call 999 or go to A&E if you get sudden chest pain, have severe difficulty breathing or start coughing up blood.
Reducing the spread
- Wash your hands often with warm water and soap.
- Cover your mouth and nose with a tissue when you cough or sneeze, or use the bend of your elbow.
- Put used tissues in the bin as quickly as possible.
The flu vaccine is offered free on the NHS each autumn to people at higher risk of serious illness. Our Flu this week page has the latest UKHSA figures and uptake so far this season.
Sources
All sources were opened and checked on the date of publication. Summaries are our own words.