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Flu is an illness caused by the influenza virus. It occurs every year, usually in winter. It is important that you protect yourself and others from flu by helping to prevent the spread of the virus and getting the flu vaccine if you are eligible.

About flu

You can catch flu – short for influenza – all year round. It's especially common in winter, which is why it's also known as ‘seasonal flu’. It usually peaks between December and March.

It's not the same as the common cold. Flu is caused by a different group of viruses. The symptoms tend to be more severe and last longer.

Symptoms of flu 

The symptoms of flu include:

Flu symptoms usually peak after two or three days and you should begin to feel much better within five to eight days. However, older people or those with certain medical conditions may develop complications that can lead to serious illness and can be life-threatening.

That is why it is important to get the seasonal flu vaccine if it is offered to you.

Telling the difference between cold and flu

Cold and flu symptoms are similar but flu tends to be more severe.

Cold symptoms:

  • appear gradually
  • affects mainly your nose and throat
  • makes you feel unwell, but your OK to carry on as normal (for example, go to work)

Flu symptoms:

  • appear quickly within a few hours
  • affect more than just your nose and throat
  • makes you feel exhausted and too unwell to carry on as normal

What to do if you have flu 

It is important to remember that for most people, flu is a mild illness that can be treated at home with rest, drinking plenty of fluids and taking medicine, such as paracetamol, as directed to control the symptoms.

If you have a high temperature and difficulty breathing, if your symptoms are getting worse over time or you haven't improved after a week, you should contact your GP or the GP out of hours service.

You should not go to an emergency department unless it is urgent and essential.

When to see your GP 

Consider visiting your GP if:

  • you're 65 years of age or over
  • you're pregnant
  • you have a long-term medical condition – such as diabetes, lung disease, kidney disease or a neurological disease
  • you have a weakened immune system – for example, because you're having chemotherapy or have HIV
  • you develop chest painshortness of breath or difficulty breathing, or start coughing up blood
  • your symptoms are getting worse over time or haven't improved after a week

In these situations, you may need medication to treat or prevent complications of flu. Your doctor may recommend taking antiviral medicine to reduce your symptoms and help you recover more quickly.

How flu is spread 

The flu virus is spread in the small droplets of saliva coughed or sneezed into the air by an infected person. If you inhale these droplets, you may become infected.

Flu can also spread if someone infected with the virus touches:

  • common surfaces such as door handles with unwashed hands
  • the hand of someone else without washing their hands first

Preventing the spread of the flu virus 

You can take simple steps to help stop the spread of the flu virus. Remember, you should always:

  • carry tissues
  • use tissues to cover your mouth and nose when you cough or sneeze
  • dispose of the dirty tissues quickly
  • wash your hands regularly


The information on this page has been adapted from original content from the NHS website.

For further information see terms and conditions.

This page was reviewed August 2018

This page is due for review April 2021

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