Published by Bupa’s Health Information Team, February 2011.
This factsheet is for people who have seasonal flu, or who would like information about it, including symptoms and causes.
Flu (or influenza) is caused by flu viruses. Seasonal flu follows a pattern and tends to occur at around the same time every year. Most people fight off the infection without medical treatment.
Seasonal flu is caused by a virus. Flu viruses can infect your nose, throat, sinuses and lungs.
There are three main types of flu virus: type A, type B and type C. Type A is the most common and the most infectious, and usually causes the most severe symptoms. Type B usually causes less serious symptoms and type C usually causes a mild infection similar to the common cold.
Flu viruses change from year to year. Every few years the flu virus changes a lot, which may cause an epidemic. This means that a lot of people become infected because very few people have immunity to the new virus. Sometimes a new virus can cause a pandemic, which means that the virus spreads quickly throughout the world, infecting large numbers of people.
Most people recover from flu after a few days or weeks. However, for older people, newborn babies and people with other health problems, for example heart disease or chest problems, flu can be more serious.
In the UK you’re most likely to get seasonal flu in the autumn and winter months, between October and April.
When you catch flu from someone, it usually takes two to three days for your symptoms to start. Flu viruses grow in the soft, warm surfaces of your nose, throat, sinuses, airways and lungs, so this is where you usually get symptoms. These can include:
Symptoms usually last for about a week but you may feel tired for a few weeks. If your child has flu he or she may also feel sick or be sick and have diarrhoea.
Most healthy adults recover completely from flu within a few weeks. However, young children, people over the age of 65 and those with other health problems are more likely to have complications from flu, which can include:
Young children can sometimes have seizures or fits, called febrile convulsions, because of their high body temperature.
You’re at greater risk of having complications from flu if you’re over 65, or if you have:
Flu viruses are very infectious. Most people catch flu by breathing in air that has the virus in it. This usually happens when people with flu cough or sneeze, which spreads the virus in droplets in the air.
You can also catch flu by direct contact with someone who has it, for example by shaking hands or by touching something they have recently touched. You pick up the flu virus on your hands and then when you touch your nose or mouth you may pass the virus onto yourself. The flu virus can live on a hard surface for up to 24 hours and on a soft surface for about 20 minutes.
You’re infectious and can spread the virus to other people when your symptoms start, and for five days afterwards. Children are infectious for longer.
Most people are able to diagnose themselves as having flu and won’t need to see their GP. However, if your symptoms get worse or if your fever and aching muscles last longer than a week, you should see your GP. You should also see your GP if you have a medical condition which may make flu worse.
Your GP will ask you about your symptoms and examine you. He or she may also ask you about your medical history. Your GP will diagnose flu from your symptoms. No other tests are usually needed.
There is no cure for flu. However, there are things you can do to make yourself more comfortable including the following.
If you have muscle pains, a headache, sinus pain or a sore throat then you can take paracetamol or ibuprofen as a painkiller. These medicines will also help to reduce a fever if you have one.
It’s important to check the dose you're taking of different types of medicines. It's easy to accidentally have more than the daily dose by using more than one product, for example tablets, capsules and a hot lemon drink that contain the same active ingredient, such as paracetamol.
Children can take paracetamol and ibuprofen as a liquid. Children under the age of 16 should not take aspirin. Talk to your pharmacist about which painkillers are suitable for your child.
If you have a blocked nose or sinuses then a decongestant may help to ease the symptoms. Nasal sprays can give you relief from a blocked nose for a few hours. Decongestant tablets may also help to ease the symptoms of blocked sinuses. However, you shouldn’t take decongestants for too long as they can cause rebound congestion. Decongestants shouldn’t be given to children under the age of six. If you have high blood pressure or problems with your liver or kidneys, you should talk to your GP before you take decongestants.
Always read the patient information leaflet that comes with your medicine and if you have any questions, ask your pharmacist for advice.
Antibiotics aren’t used to treat infections caused by a virus. Your GP may prescribe antibiotics if you develop a secondary infection caused by bacteria, such as a chest infection or an ear infection.
If you’re over the age of 65 or have other health problems which may increase your risk of complications, your doctor may prescribe an antiviral medicine. Antiviral medicines can reduce the length of time your symptoms last by around one day. However, you need to start taking antiviral medicines within two days of getting the flu. These medicines can be taken as tablets or as an inhaler (similar to the ones used for asthma).
There are a number of supplements and complementary medicines that are popular for treating colds. These include vitamin C, menthol, zinc, garlic and Echinacea. There is not enough evidence to suggest that taking these or Chinese herbal medicines are likely to be effective at treating flu.
Menthol can help to ease a blocked nose because it has a cooling sensation. It can also help to relieve the symptoms of a sore throat and cough because it contains a local anaesthetic which numbs the area.
Complementary medicines can interact with other medicines, so you should always tell your doctor or pharmacist about all of the medicines you’re taking.
If you have flu you can help to prevent it from spreading to other people by:
You may also be able to prevent yourself getting flu by being vaccinated against it. Every year new flu vaccines are made from the three viruses that are most likely to cause flu that winter. The flu vaccine should provide you with protection against seasonal flu for one year. However, the vaccine isn’t always effective in everyone.
The flu vaccine is available to everyone over 65 and is given to people at risk of developing complications from flu. This includes adults and children (over six months) who have:
Your GP may also suggest that you have the flu vaccine if:
If you’re due to have a flu vaccination you will be asked to visit your GP surgery every year between September and early November. Talk to your GP or nurse if you would like more information.
For answers to frequently asked questions on this topic, see FAQs.
For sources and links to further information, see Resources.
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This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the About our Health Information page.
Publication date: February 2011
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