Flu is an infectious and common viral illness spread by coughs and sneezes.
It's not the same as the common cold. Flu is caused by a different group of viruses. Symptoms tend to be more severe and last longer.
You can catch flu – short for influenza – all year round, but it is especially common in winter, which is why it is also known as "seasonal flu".
Flu causes a sudden high temperature, headache and general aches and pains, tiredness and a sore throat. You can also lose your appetite, feel nauseous and have a cough.
Flu symptoms can make you feel so exhausted and unwell that you have to stay in bed and rest until you feel better.
You should see a doctor if you have flu-like symptoms and you:
- are aged 65 or over
- are pregnant
- have a long-term medical condition such as diabetes, heart disease, lung disease, kidney disease or a neurological disease
- have a weakened immune system
This is because flu can be more serious for you, and your doctor may want to prescribe antiviral medication.
Antiviral medicine can lessen the symptoms of flu and shorten its duration, but treatment needs to begin soon after flu symptoms start for it to be effective.
Antibiotics are of no use in the treatment of flu because it is caused by a virus and not by bacteria.
The flu vaccine
A flu vaccine is available free on the NHS for:
- anyone over the age of 65
- pregnant women
- children and adults with an underlying health condition (particularly long-term heart or respiratory disease)
- children and adults with weakened immune systems
It is given as an annual injection to:
- adults over the age of 18 at risk of flu (including everyone over 65)
- children aged six months to two years at risk of flu
The flu vaccine is also given as an annual nasal spray to:
- children aged two to 18 years at risk of flu
- healthy children aged two, three and four years old
The flu vaccine cannot give you flu as it doesn't contain the active virus.