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Influenza is an inflammation of the respiratory tract caused by the influenza viruses. The most common virus variants, type A and B, cause seasonal epidemics in Finland between December and April. Influenza symptoms are very similar to the flu, or common cold, but the symptoms tend to present more severely. Most healthy adults contracting influenza manage in home care. People belonging to risk groups affecting their general health should contact their care provider more promptly.

Influenza can be effectively tackled with vaccinations. People belonging to risk groups should be vaccinated annually in October or November.

Contagiousness and symptoms

Influenza is transmitted through both droplet transmission, and the airborne route The incubation period varies from 1 to 7 days but is usually 2 to 3 days.

Typical symptoms are

  • high fever
  • chills
  • head ache
  • muscle aches
  • dry cough
  • nausea.

Vomiting and diarrhoea may occur. A runny nose is not a typical symptom of influenza.

During an epidemic a diagnosis can be established based on symptoms that are typical of influenza. Various testing methods have also been developed for influenza. These are, in particular, used at hospital emergency clinics.

Several complications can occur in influenza. These should be suspected if symptoms become more severe or return after they have first subsided. The most common complications in adults include pneumonia and sinusitis. Influenza can also cause worsening of asthma, for example.


  • Rest and sufficient hydration
  • To lower a high temperature and ease muscle aches, painkillers such as paracetamol 0,5 – 1 g/x3 times daily or ibuprofen 400 – 800 mg /x3 can be taken, if no contraindications present.
  • Influenza often gets better on its own after a week’s rest.

If you know you have some underlying condition and you belong to a risk group, contact a healthcare professional for assessment of the need for further treatment. If necessary, treatment with antiviral medicines can be started. In those with no underlying conditions, the benefit of antiviral medicines to recovery from influenza is considered to be so minor that the treatment is generally not recommended.

When should you seek treatment?

You should get assessed by a healthcare professional if your temperature is very high, your general health is worse than with an ordinary flu or if symptoms return after a period of subsiding first. If an influenza belongs to a risk group, medical care should be accessed more promptly.

Influenza vaccinations

In those belonging to risk groups, influenza vaccinations can reduce hospitalisations and inpatient care due to influenza, premature deaths from influenza, the incidence of severe influenza, post-influenza complications, and complications of their underlying condition. Vaccination is also recommended for those in regular close contact with someone susceptible to serious influenza. In fact, seasonal influenza vaccines are so safe that vaccination is considered worthwhile for everyone. It’s also a good idea to get vaccinated before travelling. Vaccination during an influenza epidemic can and should be carried out as these epidemics move gradually from region to region.

The composition of the vaccine is altered every year based on what strains of the virus are circulating.

Vaccine protection is acquired within about two weeks. If the vaccinated person has already contracted an influenza virus, the vaccine can no longer prevent influenza. However, in this case vaccination is not harmful.

Protecting yourself from infection 

The best way to protect yourself from any respiratory infection is to ensure good hand hygiene, to cover your nose and mouth when coughing, and to use a disposable tissue when sneezing. Face masks used during the COVID epidemic have also reduced influenza infections. When you’re ill, it’s best to avoid other people.

Information sources: The Finnish Medical Society Duodecim: Terveysportti, Lääkärin tietokanta database

FSHS General Practitioner / 12 June 2022 

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