Influenza occurs most often in winter. It is a highly infections illness caused by a flu virus. The virus infects your lungs and upper airways, causing a sudden high temperature and general aches and pains.

Is this a cold or flu?

Many of the symptoms of flu are similar to those of a common cold, and many people incorrectly refer to a heavy cold as flu.

• Symptoms of cold appear gradually, are not severe and affect your nose and throat.
• Symptoms of flu are more severe, causing fever and aching muscles. If you have flu you are likely to feel very unwell and will not be able to do your usual activities.

The causes of flu

The flu virus is contained in the millions of tiny droplets that come out of the nose and mouth when someone coughs or sneezes. These droplets can spread about one metre. They hang suspended in the air for a while but then land on surfaces, where they can survive for up to 24 hours. You can spread the virus by touching these surfaces and then touching something else.

Everyday items such as food, door handles, the remote control, handrails and computer keyboards may carry traces of the virus. People usually become infected by picking up the virus on their hands from contaminated objects and then placing their hands their mouth or nose. It is also possible to breathe in the virus when it is suspended in airborne droplets.

The symptoms of flu

If you have seasonal flu you can experience any of these symptoms:

• Sudden fever
• Dry, chesty cough
• Headache
• Tiredness
• Chills
• Aching muscles
• Limb or joint pain
• Diarrhoea or stomach upset
• Sore throat
• Runny or blocked nose
• Sneezing
• Loss of appetite
• Difficulty sleeping

Babies and small children with flu may also appear drowsy, unresponsive and floppy.

Your symptoms will usually peak after two to three days and you should begin to feel better within five to eight days. A cough and general tiredness may last for two to three weeks.

Treating flu

If you are otherwise fit and healthy, you can manage your symptoms of seasonal flu at home. Antibiotics are not prescribed for flu as they have no effect on viruses.

Make sure you have plenty of rest and take paracetamol-based cold remedies to lower your temperature and relieve symptoms.

Some over-the-counter remedies can be given to children who have flu, according to the instructions supplied with each medicine. Under-16s must not take aspirin or flu remedies that contain it. Always read the medicine’s label or check with the pharmacist that it is suitable for children to take.

Drink plenty of fluids while you are recovering. You may need to stay in bed for two or three days before your symptoms peak.

When you should see your GP

If you are in an at-risk group and have flu-like symptoms, or if your flu symptoms are getting worse, see your GP. These groups are more likely to suffer complications from flu.

The at-risk groups are those who:

• Are over 65
• Have a heart problem
• Have a chest complaint or breathing difficulties including, bronchitis, emphysema
• Have a kidney disease
• Have lowered immunity due to disease or treatment (such as steroid medication or cancer treatment)
• Have a liver disease
• Have had a stroke or a transient ischaemic attack (TIA)
• diabetes
• Have a neurological condition e.g. multiple sclerosis (MS) or cerebral palsy
• Have a problem with, or removal of, your spleen e.g. sickle cell disease
• are pregnant.

This year for the first time pregnant women have been included in the If you are pregnant you will also be offered the flu vaccination this year. This is because the H1N1 virus is circulating this winter and pregnant women who catch this strain are at an increased risk of severe disease and flu-related hospital admissions.

See your GP if the following applies to you:

• Your symptoms have got much worse, or you have developed other symptoms that are not typical of seasonal flu, such as a rash.
• Your symptoms have lasted for longer than a week.
• You have a medical condition that is making your flu worse.

For further information you can log on to NHS Direct, NHS Choices or the Health Protection Agency.