Flu (influenza) is a common infectious viral illness spread by coughs and sneezes. It can be very unpleasant, but you’ll usually begin to feel better within about a week.

You can catch flu all year round, but it’s especially common in winter, which is why it’s also known as seasonal flu.

Flu isn’t the same as the common cold. Flu is caused by a different group of viruses and the symptoms tend to start more suddenly, be more severe and last longer.

Flu symptoms

Some of the main symptoms of flu include:

• a high temperature (fever) of 38C (100.4F) or above
• tiredness and weakness
• a headache
• general aches and pains
• a dry, chesty cough

Cold-like symptoms, such as a blocked or runny nose, sneezing, and a sore throat, can also be caused by flu, but they tend to be less severe than the other symptoms you have.

Flu can make you feel so exhausted and unwell that you have to stay in bed and rest until you feel better.