Symptoms of flu

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Flu symptoms appear quickly and include:

Thermometer with a danger signal indicating fever

High fever.

Person with a cane and trembling


Nose with a drop

Blocked nose.

Nose with a drop

Runny nose.

Muscle discomfort in the back

Aching muscles.

Person with sore throat

Sore throat.

Person with persistent cough

Dry cough.

Tired woman, sweating


In most cases, the fever tends to last for 2–3 days and the malaise or tiredness may persist for up to 2 weeks.

It is worth noting that some of the symptoms and their intensity can vary greatly between different age groups. In children, for instance, flu often causes inflammation of the middle ear or gastrointestinal symptoms such as nausea, vomiting or diarrhoea, yet these are rarely experienced by adults. Whereas elderly patients tend to suffer from breathing difficulties and excessive phlegm production.

Healthy people usually recover within one or two weeks after the onset of symptoms, although some may develop complications such as bronchitis, otitis, sinusitis or pneumonia. However, influenza may worsen the underlying condition of patients with chronic heart and/or lung diseases, for example, those with asthma, diabetes, COPD or heart problems. In very rare cases, it can cause neurological complications such as Guillain–Barré syndrome.

Substantiated information by:

Anna Llupià
Antoni Trilla
Catia Cillóniz Campos
Gemina Santana

Published: 10 March 2020
Updated: 10 March 2020

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