Flu symptoms: What are the symptoms and duration of the flu?

What are the symptoms and duration of the flu: Every year, the influenza epidemic causes troublesome symptoms for millions of people in France, but also significant complications in many thousands. Doctissimo presents the signs of this viral disease, as well as its average duration (Flu symptoms).

Influenza is abundantly described in older medical books. This is one of the oldest viral diseases . However, there is sometimes a tendency to use the term flu for a set of diseases that do not fall under the influenza virus , but a simple Flu symptoms condition.

Flu symptoms: What are the symptoms and duration of the flu?

People who are sick with flu often feel some or all of these symptoms:

Symptoms of influenza status vs those of true flu


Flu symptoms: Several features distinguish the flu syndrome from the true flu. The symptoms of ILI are often transient and of moderate intensity . Those responsible for these “false flu” are syncytial respiratory viruses (RSV), para-influenza virusesadenoviruses , rhinoviruses , enteroviruses , coronaviruses …


On the other hand, the real influenza, seasonal and viral , is characterized by symptoms of a strong intensity occurring suddenly :

  • An intense fever (around 39 ° C);
  • severe fatigue (asthenia);
  • Of headaches (headaches);
  • Aches and pains  (muscle pain and diffuse joint);
  • the chills ;
  • Sometimes a cough  and nasal congestion …

Far from being as harmless as its counterparts, the influenza virus remains in France one of the leading causes of infectious mortality . He is responsible each year for several thousand deaths .

Influenza viruses (Influenza)

The influenza virus belongs to the family Orthomyxoviridae and genus Influenzavirus , of which there are three types A, B and C . Type A and B viruses are responsible for annual influenza epidemics, but only influenza A viruses cause influenza pandemics . Type C virus seems to be linked to sporadic cases.

Type A viruses are the most common and most virulent ; several subtypesare distinguished on the basis of their surface antigens, hemagglutinin (H1 to H16) and neuraminidase (N1 to N9). This gives therefore 144 possible combinations , but for the seasonal flu , the viruses involved boils down to H1, H2, H3 and N1 or N2 responsible for the annual flu.

Duration of incubation, contagion and recovery of influenza

The incubation time of the flu (between the virus contamination and the first symptoms) varies between 24 and 48 hours . The patient is contagious for an average period of six days , including before the symptoms appear. The flu is transmitted by secretions: coughing, postilions, sneezing but also by contact with an infected person or objects affected and contaminated (door handle …). In non-compromised individuals, recovery is complete after one to two weeks .

Life expectancy of the virus 

The flu virus has a variable lifespan, it:

  • 5 minutes on the skin;
  • a few hours in the dried secretions;
  • 8 to 12 o’clock on handkerchiefs, clothes, papers etc;
  • several days on inert surfaces (buttons, door handle ..).

Vaccination against the flu

The vaccination against influenza is recommended for:

  • The pregnant women , regardless of trimester;
  • People, including children from the age of 6 months, with the following pathologies:
    • Chronic bronchopulmonary disorders meeting the criteria of ALD 14 ( asthma and COPD );
    • Obstructive or restrictive chronic respiratory insufficiencies regardless of the cause, including neuromuscular diseases at risk for respiratory decompensation, upper or lower airway malformations, lung malformations or chest malformations;
    • Chronic respiratory diseases that do not meet the ALD criteria but may be aggravated or decompensated by an influenza condition, including asthma , chronic bronchitis, bronchiectasis, bronchial hyperresponsiveness;
    • Bronchopulmonary dysplasia;
    • Cystic fibrosis ;
    • Cyanogenic congenital heart disease or with PAH and / or heart failure,
    • Serious heart failure ;
    • Severe valvulopathies;
    • Serious heart rhythm disorders warranting long-term treatment;
    • Coronary diseases;
    • history of stroke ;
    • Severe forms of neurological and muscular affections (including myopathy , poliomyelitis , myasthenia , Charcot’s disease ),
    • Paraplegia and quadriplegia with diaphragmatic involvement,
    • Severe chronic nephropathies ,
    • Nephrotic syndromes,
    • Sickle cell anemia , homozygous and heterozygous double S / C, spa-SCD
    • Diabetes type 1 and type 2,
    • Primitive or acquired immune deficiency (oncological and hematologic diseases, hematopoietic organ and stem cell transplants, hereditary immune deficiency, inflammatory and / or autoimmune diseases receiving immunosuppressive therapy), except persons who receive regular treatment with immunoglobulins; persons infected with HIVirrespective of age and immunovirological status,
    • Chronic liver disease with or without cirrhosis ;
  • The obese individuals with a body mass index (BMI) greater than or equal to 40 kg / m2, without or pathology associated with a disease other than those mentioned above;
  • The people staying in a care facility following and in a medico accommodation facility regardless of age;
  • Family circle of infants less than 6 months of age, with defined risk factors for severe influenza : premature babies , especially those with broncho-dysplasia-type sequelae, and children with congenital heart disease, congenital immune deficiency, pathology pulmonary, neurological or neuromuscular or long-lasting condition.

Vaccinations need to be renewed every year as new strains of influenza virus appear and change constantly. Influenza epidemics can occur from October to March . The best time to get vaccinated is from October to mid-December, 15 days is needed for your body to produce antibodies for your protection.

Treatment of flu

In people who are not particularly fragile , the body is able to effectively fight the infection with a little rest , good rehydration and  antipyretic drugs (fever). The advice is simple:

  • Stay in bed ;
  • Drink a lot ;
  • To clear the nose ;
  • Treat the fever .

For the children , some peculiarities are necessary. The choice of the antipyretic depends on its age , your doctor will judge the utility of using this or that drug. To find out more, read them in our article ” Influenza, how to reduce children’s fever? “.

It is also possible to use antivirals , which can reduce the duration and intensity of symptoms. There are two classes today:

  • Inhibitors of viral M2 protein ( amantadine and rimantadine) are active against influenza A viruses, but have some disadvantages: they have poor renal , hepatic and neurological tolerance . In addition, resistances appear quickly;
  • Neuraminidase inhibitors (zanamivir – Relenza ® – and oseltamivir – Tamiflu ®) would be effective in reducing the intensity and duration of symptoms if they are given within 48 hours of the onset of symptoms. These drugs also have a preventive action against the infection of the flu. But a study * published in 2012 covering all the work concerning oseltamivir ( Tamiflu ®) reaches more disappointing conclusions about its effects. By including published and unpublished double-blind studies comparing this drug with placebo, the benefits would be limited to reducing the duration of the 20-hour symptoms if the drug is taken within 24 hours of the first symptoms. No statistically significant reduction in serious complications (pneumonia or hospitalization) was noted by the authors. What to review its usefulness in case of an influenza pandemic?

Recall that the usefulness of antibiotics  is limited to the prevention of complications of influenza (bacterial infections). They are totally helpless against the virus.

Prevention of flu 

Simple actions help to limit contamination:

  • Wash hands regularly with soap and water or with a water-based solution;
  • Cover your mouth as soon as you cough or sneeze, and teach children to do the same;
  • Wear a mask  ;
  • Limit contacts and avoid too busy places when you are contaminated;
  • Aerate your home every day. thanks for reading What are the symptoms and duration of the flu.

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