Flu & Cold

Flu & Cold
International Classification (ICD) J00


A cold (flu-like infection) is an infection of the upper respiratory tract that is triggered by viruses. These viruses are particularly easy to transmit to other people. In many cases, secondary infections with bacteria occur. A cold should not be confused with the flu. The flu is also caused by viruses, but usually has a more severe course.

A cold, on the other hand, is usually quite harmless and passes after about a week. It occurs more frequently in the autumn and winter months. It can be assumed that everyone catches a cold about two to four times a year.


There are over 100 different viruses that can cause a cold (flu-like infection). These are transmitted to other people by droplet infection, i.e. by coughing or sneezing. The incubation period is about two to five days.

Initially, the viruses attack the nose and throat. From there, they can spread to the bronchial tubes (acute bronchitis) or sinuses. Cold viruses can survive for several hours on the surface of the skin, which is why you should wash your hands thoroughly after every time you blow your nose.

If the fingers, nose, toes and ears cool down in the cold season, optimal conditions are created for viruses and thus also for a cold. It is assumed that the local immune defence is also weakened with the cooling. A weakened immune system facilitates the path of invading viruses.


The various symptoms that indicate a cold include:

  • Runny nose: initially, a watery-clear secretion is formed, which over time takes on a thick consistency and turns greenish-yellow in the case of a bacterial infection. As the nasal mucous membranes are swollen, breathing through the nose is difficult (blocked nose).
  • Occasionally there is a feeling of pressure in the ears as the sinuses close up.
  • In the early stages of a cold, tiredness and dejection may set in (general feeling of illness). In addition, mild fever, cough, as well as headache, limb pain or toothache may also occur.


The diagnosis can usually be made on the basis of the characteristic features, as well as a physical examination (clinical diagnosis). If the course is more severe, other diseases such as a real flu may have to be considered.

When examining bacterial and viral infections, particular attention should be paid to the colour of the mucus secreted. If this has a greenish tinge, there is probably a bacterial infection. To be on the safe side, a blood test can provide further information. In many cases, a viral infection is later joined by a bacterial infection (secondary infection).


If the first cold symptoms appear and subside after one to two weeks, a visit to the doctor can be dispensed with. In order to achieve a quick recovery, it is usually sufficient to observe physical rest and to ensure sufficient fluid intake (hot tea). Possibly also inhalation can provide a reduction of the complaints. Home remedies such as calf compresses or homemade cough syrup can also bring healing.

Nasal drops help to reduce the swelling of the nasal mucosa and make breathing easier. However, care should be taken not to use the drops for longer than ten days. In the longer term, nasal sprays with saline solution (such as seawater sprays) can be used. Steam inhalations with saline dissolved in water also have a decongestant effect. If you suffer from pain, taking paracetamol or ibuprofen can provide relief.

Further measures for a cold are:

  • Sleep with your head elevated
  • Avoid cigarette smoke (both active and passive), as this causes irritation of the mucous membranes.
  • Dispose of used tissues immediately to minimize the risk of infection.
  • Wash and disinfect your hands at regular intervals, otherwise you will infect yourself and others again and again.
  • Get enough sleep, as this supports the immune system in its fight against the pathogens. Stress should also be avoided as much as possible, as it weakens the immune system.
  • A varied diet with sufficient vitamins and minerals strengthens the immune system. Vitamin C supplements, on the other hand, are usually useless when you have a cold.
  • Heavy physical exertion and sport should be avoided during a cold. Otherwise, inflammation of the heart muscle (myocarditis) cannot be ruled out.


In most cases, a cold does not pose a great danger and subsides after one to two weeks. Rarely, however, complications can arise, such as inflammation of the eye, sinuses, middle ear, throat or lungs.

The reason for a possible secondary illness of an influenza infection can be a secondary infection with viruses, which is added to the existing bacterial infection. If this is the case, it makes sense to consult a doctor. Bacteria can usually be treated with antibiotics.


You can prevent a cold by doing the following:

  • Avoid touching your face after contact with a person with a cold.
  • If possible, it is advisable to keep your distance from a person with a cold.
  • Thorough hand hygiene is very important. This is useful both for the person with the cold and for people who are in contact with them
  • Cold and dampness should be avoided
  • Getting enough sleep is important
  • A balanced diet rich in vitamins is essential to strengthen the immune system.
  • Measures such as regular visits to the sauna or Kneipp cures strengthen the body's defences against cold germs.

Editorial principles

All information used for the content comes from verified sources (recognised institutions, experts, studies by renowned universities). We attach great importance to the qualification of the authors and the scientific background of the information. Thus, we ensure that our research is based on scientific findings.
Danilo Glisic

Danilo Glisic

As a biology and mathematics student, he is passionate about writing magazine articles on current medical topics. Due to his affinity for facts, figures and data, his focus is on describing relevant clinical trial results.

The content of this page is an automated and high-quality translation from DeepL. You can find the original content in German here.



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