Flu 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 – short for influenza – all year round, but it’s especially common in winter, which is why it’s also known as “seasonal flu”.
It’s not 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.