Flu is a highly infectious and very common viral illness that is spread by coughs and sneezes.
It’s not the same as the common cold. Flu is caused by a different group of viruses and symptoms tend to be more severe and last for 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 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.
More details about the symptoms of flu, how to treat it, when to see a doctor and how to prevent getting flu can be found on the NHS Choices website.