Flu (Influenza)

Influenza is a common infectious viral illness passed by coughs and sneezes. It has a short incubation period and symptoms come on quickly. A person with flu may feel very tired and poorly for one to two weeks and some high-risk groups face potential complications.

Incubation period

1-3 days

Symptoms

Sudden onset of a high fever, Chills, Headache, muscle aches and joint pain, Cough (usually dry), Sore throat, Nasal congestion and runny nose, Fatigue

Possible complications

Bronchitis, Pneumonia, Tonsillitis, Sinusitis

About Influenza

Influenza (flu) is a common infectious viral illness spread by coughs and sneezes. You can catch flu all year round but it’s especially common in winter, which is why it’s often referred to as seasonal flu.

Flu is not the same as a common cold; it’s caused by a different group of viruses. The symptoms tend to start more suddenly, be more severe and last longer. You may be so tired and unwell with the flu that you need to rest in bed for a week or two.

Flu symptoms

Influenza has a short incubation period of one to three days and the symptoms tend to come on suddenly. They typically include:

  • Sudden onset of a high fever
  • Chills
  • Headache, muscle aches and joint pain
  • Cough (usually dry)
  • Sore throat
  • Nasal congestion and runny nose
  • Fatigue

Stomach symptoms such as nausea, vomiting and diarrhoea may occur and are more common in children than adults.

The flu can make you feel very poorly for a week or two but most people usually recover fully within that time. Some people, especially the elderly, may feel weak for a long time, even after their symptoms have gone away.

Possible flu complications

Complications of flu mostly affect people in high-risk groups, such as the elderly, pregnant women and those who have a long-term medical condition or weakened immune system.

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

In some cases, flu can make existing conditions such as asthma or chronic obstructive pulmonary disease (COPD) worse. It may also affect blood sugar levels in people with diabetes.

Rarer complications from flu include meningitis, seizures, encephalitis (swelling of the brain), tonsillitis, sinusitis, or otitis media (a middle ear infection).

Influenza can very occasionally become life-threatening, especially in high-risk groups.

Influenza FAQs

The flu is caused by influenza viruses that infect the nose, throat, and lungs. These viruses spread when people with flu cough, sneeze or talk, sending droplets containing the virus into the air and potentially into the mouths or noses of people who are nearby. You can also get the flu by touching a surface or object that has the flu virus on it and then touching your mouth, eyes or nose.

Though pandemic flu occurs infrequently, flu (caused by one of the three main influenza viruses) is ever-present, though more prevalent in the winter, with localised epidemics occurring every few years.

While your doctor may test your child for flu, they may decide it’s not necessary. Often, it’s possible to diagnose someone with flu based on the symptoms alone (one of the main indicators of the flu is the speed with which symptoms begin).

There are several tests available to detect flu viruses. Your doctor will advise you if they think you or your child need a test.

Treatment involves rest, plenty to drink and a drug such as paracetamol to lower the fever. Most people recover within two weeks. Antibiotics are of no help with flu itself but may be necessary to treat any ‘secondary’ infections of, typically, the chest or ear.

If you or your child do get sick, it’s recommended that you speak to your GP, especially if you or they are at high risk for complications. Antiviral medications can help to reduce the severity of flu and how long you’re ill.

The cough caused by the flu usually results in asthma-like symptoms and asthma medication can help to provide relief – again, this is something you should discuss with your GP.

A yearly flu vaccine is the best way to prevent catching the most common strains of the illness.

Flu statistics

Influenza is not a notifiable disease, which means that cases don’t have to be reported. As a result, we don’t know the number of cases in the UK or worldwide over the past 12 months.

Public health data for communicable diseases in the UK (where known) is published by the Royal College of General Practitioners and can be found here.

You can search the Office for National Statistics (ONS) website for the most recently published information about deaths where the flu was registered as an underlying cause.

Death certificates record that fewer than ten children die from flu in the UK in most years. However, it’s possible that these figures under-record deaths from flu as ‘statistical modelling’ estimates that, on average, between 40 and 50 children actually die from flu yearly, though many, if not most, will have underlying health problems. The vast majority of flu deaths occur in adults over 70.

Individual advice about protecting your child against the flu

Need advice about whether your child should have the flu jab or nasal spray? The BabyJabs clinicians are here to listen and answer your questions to help you decide.