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. You generally start to feel ill within a few days of being infected.

Flu symptoms can make you feel so exhausted and unwell that you have to stay in bed and rest. Symptoms peak after two to three days and you should begin to feel much better after a week or so, although you may feel tired for much longer.

Elderly people and anyone with certain long-term medical conditions are more likely to have a bad case of flu, and are also more likely to develop a serious complication such as a chest infection.

In the UK, about 600 people a year die from a complication of seasonal flu. This rises to around 13,000 during an epidemic.

The flu jab

Flu jabs are available for a small fee at many local pharmacies, so there is no need to visit your doctor. The flu vaccine is also available free on the NHS if you:

• are pregnant
• 65 or older
• have a serious medical condition
• are a healthcare worker or carer
• live in a residential or nursing home

The flu vaccine is available from October each year. If you think you need it, talk to your GP or local pharmacy.

When to see a doctor

If you are otherwise fit and healthy, there is usually no need to see a doctor if you have flu-like symptoms. The best remedy is to rest at home, keep warm and drink plenty of water to avoid dehydration. You can take paracetamol or ibuprofen to lower a high temperature and relieve aches.

You should see a doctor if you have flu-like symptoms and you:

• are 65 or over
• are pregnant
• have a long-term medical condition such as diabetes, heart disease, lung disease, kidney or neurological disease
• have a weakened immune system

This is because flu can be more serious for you, and your doctor may want to prescribe antiviral medication.

Preventing the spread of flu

The flu virus is spread in the small droplets of fluid coughed or sneezed into the air by an infected person. These droplets can travel a metre or so and infect anyone within range who breathes them in.

You are usually infectious for five or six days from the day before your symptoms start. Children and people with weaker immune systems, such as cancer patients, may remain infectious for longer.

Flu can also spread if someone with the virus transfers it on their fingers. For example, if you have flu and you touch your nose or eyes and then touch someone else, you may pass the virus on to them. Similarly if you have flu and touch common hard surfaces such as door handles with unwashed hands then other people who touch the surface after you can pick up the infection.

Besides getting the flu vaccine, you can stop yourself catching flu or spreading it to others by being careful with your hygiene.

Always wash your hands regularly with soap and water, regularly clean surfaces such as your keyboard, telephone and door handles to get rid of germs, use tissues to cover your mouth and nose when you cough or sneeze and put used tissues in a bin as soon as possible.

You can also help stop the spread of flu if you avoid all unnecessary contact with other people while you're infectious. You should stay off work until you are no longer infectious and you are feeling better.