Flu, seasonal
Flu, seasonal

Flu is a common illness, caused by a virus and easily spread by coughs and sneezes. It can be very unpleasant, but most people begin to feel better within about a week.

You can catch flu – also known as influenza – all year round, but it's especially common in the winter season, which is why it's sometimes called "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.  Flu can be very serious for some people.

Some of the main symptoms of flu include:

  • a high temperature (fever) of 38C (100.4F) or above
  • tiredness and weakness
  • headache
  • general aches and pains
  • a dry, chesty cough

A blocked or runny nose, sneezing, and a sore throat – can also be caused by flu.

Flu can make you feel so exhausted and unwell that you have to stay in bed and rest until you feel better. Some people are more at risk to complications if they get flu than others, this includes the very young, the elderly, pregnant women and those with long term health conditions.

NHS 111 Wales has a cold and flu symptom checker  that you can use.

Read more about the symptoms of flu.

What to do

If you're otherwise fit and healthy, with no long term health problems, there's usually no need to see a doctor if you have flu-like symptoms.

People who are more at risk of complications if they catch flu such as the very young, elderly, pregnant or with a long term health condition should seek medical advice promptly as they may need antiviral medicines to reduce the risk of them becoming very unwell.

The best remedy for most people 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 if necessary.

Flu spreads easily so stay off work or school until you're feeling better. For most people, this will take about a week.

Read more about treating flu at home.

You can help reduce the chances of spreading flu by remembering to Catch it, Bin it, Kill it –

  • Catch coughs and sneezes in a tissue
  • throw the tissue in a bin and
  • wash your hands to kill the virus

When to see your GP

Some people are more at risk of becoming very ill if they catch flu than others and you should speak to your GP surgery if you think you have flu and:

  • are 65 years of age or over
  • are pregnant
  • have a long-term medical condition – such as diabetes, heart disease, lung disease, kidney disease, liver disease, have had a stroke or mini stroke, or a neurological disease or if you are very overweight (BMI of 40 or above)
  • have a weakened immune system – for example, because you're having chemotherapy or have HIV

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.

Read more about antiviral medication for flu.

It is also important to talk to your GP surgery if:

How long does flu last and is it serious?

If you have flu, you generally start to feel ill within a few days of being infected.

You will probably begin to feel much better within a week or so.

You will usually be most infectious from the day your symptoms start and for a further three to seven days. Children and people with weaker immune systems may remain infectious for longer. Some people are infectious and have no symptoms.

Most people will make a full recovery and won't experience any further problems, but elderly people, the very young, pregnant women and people with certain long-term medical conditions are more likely to have a bad case of flu or develop a serious complication, such as a chest infection.

Some people are infected with flu and have no symptoms, but they can still pass it on.

Read more about the complications of flu.

How you catch flu

Flu viruses are contained in the millions of tiny droplets that come out of the nose and mouth when someone who is infected coughs or sneezes.

These droplets typically spread about one metre. They hang suspended in the air for a while before landing on surfaces, where the virus can survive for up to 24 hours.

Anyone who breathes in the droplets can catch flu. You can also catch the virus by touching the surfaces that the droplets have landed on if you pick up the virus on your hands and then touch your nose or mouth.

Everyday items at home and in public places can easily become contaminated with the flu virus, including food, door handles, remote controls, handrails, telephone handsets and computer keyboards. Therefore, it's important to wash your hands frequently.

You can catch flu many times, because flu viruses change regularly.

Preventing the spread of flu

The best way to prevent spreading flu is to have a flu vaccine every year, but you can also help reduce the chances of catching flu or spreading it to others with good hygiene measures.

Always wash your hands regularly with soap and warm water, especially after you have sneezed. Always catch the sneeze in a tissue and throw the tissue straight in the bin, then wash your hands thoroughly to kill the virus. As well as:

  • regularly cleaning surfaces such as your computer keyboard, telephone and door handles to get rid of germs
  • using tissues to cover your mouth and nose when you cough or sneeze
  • putting used tissues in a bin as soon as possible

You can also help stop the spread of flu by avoiding unnecessary contact with other people while you're infectious. You should stay off work or school until you're feeling better.

People more at risk of serious illness if they catch flu, should have an annual flu vaccine (see below) and if they are exposed to flu antiviral medication may be recommended to help reduce the risk of becoming infected.

Read more about how to stop the spread of flu.

The flu vaccine

The following groups are eligible for free NHS flu vaccination in Wales:

  • those aged 65 years and over (defined as those 65 and over on 31 March 2020 (i.e. born on or before 31 March 1955).
  • those aged six months to under 65 years in a clinical risk group (see below)
  • pregnant women
  • very overweight adults (have a BMI of 40 or above)
  • those who live in long-stay residential care homes
  • carers
  • care home workers with regular direct client contact

An annual flu vaccine nasal spray is now offered to children aged two to ten years old. Two and three year olds will generally have their vaccine at their GP surgery, and four to ten year olds will have their vaccine in school. The following groups of children are eligible for free NHS flu vaccination in Wales:

  • all two and three year olds (age on 31 August 2019)
  • all children in primary school (reception class to school year 6)
  • children from 6 months of age with a long term health condition should have a flu vaccine, for those under two this will be an injection, for those aged 2 and over it will be a nasal spray.

People with any of the long term health conditions below are considered at increased risk of flu and its complications and should have annual flu vaccination:

  • Chronic chest disease (including moderate to severe asthma)
  • Chronic heart disease
  • Chronic kidney disease (from stage 3)
  • Chronic liver disease
  • Chronic neurological disease (including stroke or mini stroke)
  • Diabetes (including diet controlled)
  • Poor immune system (due to a health condition or treatment)
  • Poorly functioning spleen (or have had their spleen removed)
  • very overweight (BMI of 40 or above)

The best time to have the vaccine is in the autumn, before flu starts to circulate. You should have the flu vaccination every year so you stay protected, as the viruses that cause flu change every year.

For more information on who should have a flu vaccine and how to get it:

Antiviral medications

In 2009, the National Institute for Health and Care Excellence (NICE) recommended that doctors shoulder consider treating people in the at-risk groups mentioned above with the antiviral medications oseltamivir (Tamiflu®) or zanamivir (Relenza®) to reduce the risk of complications of flu. GPs may prescribe these medicines when flu is circulating.

Antivirals work by stopping the flu virus from multiplying in the body. They won't cure flu, but they may help slightly reduce the length of the illness and relieve some of the symptoms.

For more information, read the NICE guidelines on antivirals to treat influenza.


Antibiotics treat bacterial infections so aren't prescribed for flu as they have no effect on viruses, although they may be prescribed if you develop a complication of flu, such as a bacterial chest infection.


Flu can affect anyone of any age, but complications of flu mostly affect people in high-risk groups such as the very young, elderly, pregnant women and those who have a long-term medical condition or weakened immune system.

This is why it's important for people in these groups to have the annual flu vaccination and consider seeing their GP quickly if they develop symptoms of flu.

Flu can also be very serious for young children. That is why children with long term health conditions can have a flu vaccine from 6 months of age, and why all children aged 2-10 are now offered the annual nasal spray flu vaccine. It helps protect them from catching and spreading flu.

Chest infections

The most common complication of flu is a bacterial chest infection, such as bronchitis. Occasionally, this can become serious and develop into pneumonia.

A course of antibiotics usually cures a chest infection or pneumonia, but it can very occasionally become life-threatening, particularly in the frail and elderly or people whose immune system isn't working very well.

Worsening of existing conditions

In some people with long-term health conditions, getting flu can make their condition worse.

For example, people with lung conditions such as moderate to severe asthma or chronic obstructive pulmonary disease (COPD) may find that their symptoms become more severe when they get the flu.

In people with diabetes, flu can affect blood sugar levels, potentially causing hyperglycaemia (high blood sugar) or, in people with type 1 diabetes, diabetic ketoacidosis (a dangerous condition caused by a lack of insulin in the body).

If you have type 1 diabetes or have type 2 diabetes and take insulin, it's a good idea to monitor your blood sugar level more closely while you’re feeling unwell.

Pregnancy complications

If you get flu while you're pregnant, there's a small risk that the infection could cause problems with your pregnancy.

Flu may cause you to go into premature labour, or it may result in your baby having a low birth weight.

Occasionally, getting flu during pregnancy can result in a miscarriage or stillbirth.

This is why flu vaccine is recommended for pregnant women; to protect them, and their unborn baby. When a pregnant woman has a flu vaccine it also offers some protection to the baby in their first few months of life.

Rare complications

Rare complications of flu include:

  • tonsillitis
  • otitis media (a build-up of fluid in the ear),
  • sinusitis – inflammation of the lining of the sinuses (small, air-filled cavities behind your cheekbones and forehead)
  • febrile seizures (convulsions) – a fit that can happen when a child has a fever
  • meningitis (infection in the brain and spinal cord)
  • encephalitis (inflammation of the brain).
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The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website nhs.uk
Last Updated: 11/05/2020 07:04:45