Flu Definition

According to abbreviationfinder.org, the flu or influenza is a common viral disease that occurs mostly in autumn or winter in Europe. The flu should not be confused with influenza or gastrointestinal flu.

What is flu?

Influenza is caused by the influenza virus. They attack the mucous membrane of the respiratory tract, allowing the penetration of bacteria or other substances that trigger an infection.

Especially in the main flu season, which is between December and April in the northern hemisphere, flu epidemics often occur because the flu is very contagious.

About ten to twenty percent of the population contract influenza every year. Occasionally, global epidemics or pandemics arise, such as bird flu or swine flu.


The triggers for flu are the influenza viruses, which are transmitted from person to person via droplet infection, i.e. through sneezing or coughing. Already in the incubation period, the time between the infection and the onset of the disease, the sick person can infect other people.

When it comes to flu, there are generally three different types of flu: The influenza A virus is the most common pathogen. Due to its ability to make small genetic changes, influenza epidemics occur year after year. Due to these changes, the body has no defense against the influenza A virus.

The influenza B virus is the flu virus that primarily affects children and young people. However, the course is much milder than that of the influenza A virus.

The influenza C virus is now very rare, especially in older people who no longer have a strong immune system.

Symptoms, Ailments & Signs

In about 80 percent of cases, the flu goes unnoticed or only manifests itself as mild cold symptoms that quickly subside. In the remaining cases, infection with influenza causes serious symptoms and disorders. The typical signs of flu usually appear suddenly and after just one or two days. At the beginning there is a slight shivering and an increasing feeling of illness.

This can be accompanied by a sore throat, dry cough, watery eyes and high fever. Nausea and vomiting as well as headaches and body aches are also typical symptoms. Patients also feel tired and listless, and physical and mental performance is limited. If things go well, the symptoms subside within a few days to a week.

In severe cases, complications can occur. Then there is often inflammation of the lungs, ears or myocardium and a strong feeling of discomfort that increases as the disease progresses. If left untreated or treated too late, flu can permanently damage the heart. Possible complications of the heart, such as chronic pericarditis or an acquired heart defect, manifest themselves, among other things, in cardiac arrhythmias and reduced resilience.


After infection, the flu usually begins with a feeling of being “unwell”. There, high fever, body aches and headaches and exhaustion are often the first signs of an approaching flu.

Typical symptoms of influenza are the sudden onset of illness, with the above-mentioned malaise and a high fever above 39°C. There are also chills, as well as muscle and body aches.

Constant tiredness, exhaustion and a feeling of weakness are also typical symptoms of flu, as the body is fully focused on fighting off the influenza virus.

Characteristics that apply to a normal cold also occur in the flu. For example, headache, sore throat, dry cough and sensitivity to light. However, the symptoms of the flu are more severe than those of a common cold.


In the case of influenza flu, there is an increased risk of complications, especially in children, the elderly and people who suffer from an immune deficiency. In the worst case, the disease can even be fatal. Pneumonia is one of the most common consequences of severe flu.

In some cases, the lungs are immediately infected by the influenza viruses, which medical professionals refer to as primary influenza pneumonia. However, it is also conceivable that the lungs are attacked by bacteria due to the weakened defense system. We are then talking about secondary influenza pneumonia. Sometimes there are also mixed forms of both variants.

The influenza virus clears the way for bacterial pathogens such as Staphylococcus aureus or pneumococci to a certain extent on the respiratory mucosa. The germs can now penetrate more easily and cause pneumonia or middle ear infections. If the patient suffers from a weakened immune system, the secondary infection can take a severe course. The result is usually a high fever, which in turn puts a heavy strain on the heart and circulatory system.

Rarely, flu complications occur outside of the lungs. This is usually Reye’s syndrome, which usually occurs in children. There is a risk of damage to the brain and liver in connection with an influenza B infection and the intake of acetylsalicylic acid. However, since children have been taking less aspirin, this complication has decreased significantly.

Other complications of influenza, which are rare, include inflammation of the brain (encephalitis), inflammation of the heart muscle (myocarditis) and severe damage to muscle tissue.

When should you go to the doctor?

A serious flu should not be underestimated and should be treated by a doctor. In the worst case, it can even lead to the death of the patient. However, flu should always be distinguished from a cold, which can usually be treated with simple home remedies. A visit to the doctor is necessary for the flu if the person affected is suffering from a very high fever that does not go away on its own.

A strong cough and hoarseness also indicate the flu. Most sufferers also have body aches and nausea or loss of appetite. There is also vomiting and a strong runny nose and chills. In the case of flu, bed rest should be observed so that it is not procrastinated. If the symptoms last longer than usual, a medical examination should be carried out. A visit to a general practitioner or pediatrician is usually sufficient. Only in serious cases do those affected have to stay in a hospital as an inpatient.

Treatment & Therapy

The main treatment for the flu is to relieve the symptoms. Administering medication, for example a neuramidase inhibitor, blocks the enzyme neuramidase so that the flu can no longer multiply.

Lighter symptoms, such as fever or body aches, can be alleviated with simple painkillers. Since the immune system is very weak at the time of the disease, secondary infections such as pneumonia can result. To prevent this, other antibiotics are administered, which are very effective against the bacteria.

In addition to treatment by the doctor, the patient can also do something to make the flu weaken more quickly. Bed rest should be maintained during an illness so that the entire organism can recover and you should also drink enough, as a lot of fluid is lost due to the fever.

In addition, antipyretics, such as calf wraps, should be used. Vaccination is recommended to prevent seasonal flu.


The flu is a serious illness, which in many cases heals without complications. Nevertheless, consistent follow-up care is required to avoid recurrence of the disease or superinfection with bacteria. Follow-up care is initiated and, if necessary, monitored by the attending physician, usually the general practitioner.

In particular, patients with serious or chronic comorbidities, pregnant women, people with weak immune systems, the elderly and small children should follow their doctor’s aftercare instructions. Then complete remission of the flu without recurrence can be realized to a large extent. Healthy living and rest are the two factors on which flu follow-up care is based.

First and foremost, this means not putting strain on the body too early. Sport may only be practiced after consultation with the doctor in order not to expose the cardiovascular system to great stress too early. The immune system also needs time to rest in order to be able to regenerate in the long term. Adequate drinking serves to stabilize the circulatory system and to compensate for fluid loss through sweating in the event of a fever.

A healthy diet also stabilizes the immune system of the body, which is often severely weakened by the flu. The effects of cold should be avoided during the aftercare period. In this context, cold feet are just as unfavorable as drafts. Sufficient sleep also helps the body to regenerate.

Outlook & Forecast

In many cases, influenza heals completely and without complications in both adults and children. However, the prognosis can worsen, especially if the doctor’s instructions are not followed or only inadequately followed.

Bed rest and rest are very important when you have the flu. If this is not observed, the flu can be delayed and lead to the sometimes life-threatening heart muscle inflammation. A deterioration in the already weakened general condition of the patient can also be triggered by not drinking enough with the risk of dehydration. This can lead to febrile seizures, especially in young children. Other possibilities that can worsen the prognosis are symptoms such as loss of consciousness or drop in blood pressure.

The flu can also worsen locally in its prognosis if it does not heal properly. In the area of ​​the nose and the paranasal and frontal sinuses, accumulation of secretions can lead to pain and chronic findings. In the area of ​​the descending airways, chronic bronchitis or pneumonia can negatively affect the prognosis.

Strong involvement of the tonsils can lead to the tonsils becoming severely fissured and then no longer able to function properly. Then there is often the sometimes problematic change of floor to the bronchi and lungs. A dry cough, which often occurs at the end of the flu, can also worsen the prognosis if it causes a hyperreactive bronchial system.

You can do that yourself

If you have the flu, you should always consult a doctor. The usual measures are recommended to accompany this: bed rest and physical rest, drinking a lot and light food. Further measures depend on the prevailing symptoms.

Inhaling tea or salt water at 42 to 47 degrees helps against coughs, colds and swallowing difficulties. Acute colds can be alleviated by decongestant nose drops or herbal preparations from specialist shops. A gentle alternative is rinsing your nose with lukewarm water or chamomile tea.

If you have a severe sore throat, gargling with sage tea or preparations from the pharmacy is recommended. Essential oils and solutions from various medicinal plants such as chamomile, lemon balm, ginger or anise have also proven their worth. High fever can be counteracted with calf wraps and cooling pads, among other things.

If in doubt, however, an ambulance should be called, as high temperatures can sometimes be life-threatening. Otherwise, the following applies: pay attention to a humid climate in the bedroom. However, drafts or cold should be avoided. If you have the flu, you should always keep your chest, feet and neck area warm.