International Classification (ICD) J18.-


Pneumonia is caused by pathogens of various types, such as bacteria, fungi or viruses attacking the lung tissue. In response, there is inflammation of the deeper parts of the lungs, as well as the air sacs (aleveoli) and/or the connective tissue that lies between them. As a result, swelling and increased blood flow occur in the affected area of the lung.

A certain type of bacteria (Streptococcus pneumoniae = Pnemococcus) is found in about 30 to 60 percent of all pneumonia cases in patients of younger age. In industrialized countries, pneumonia is the most common infectious disease leading to death. Worldwide it is in third place.

In Germany, there are approximately 10 new cases of Community Acquired Pneumonia (AEP) per 1000 people. Most pneumonias are of bacterial origin. The risk group includes mainly infants, young children and the elderly. For people whose immune system is otherwise intact and who are healthy, pneumonia does not pose a great danger. It usually heals without lasting consequences.

For older people, however, as well as children and people with a weakened immune system, pneumonia can have fatal consequences. Pneumonia that originates and develops in the hospital poses a particularly great danger.


The cause of pneumonia is usually an infection with bacteria, viruses and rarely also with fungi and parasites. In 90 percent of cases, bacteria are the trigger for "Ambulatory Acquired Pneumonia".

Pneumonia can also be caused by corrosive irritants (such as poisonous gases), inhaled dyes, medications, as well as radiation therapy. Inhalation (aspiration) of stomach contents is also considered a trigger.

Some heart diseases cause water retention in the lungs (pulmonary oedema) if left untreated. This creates good conditions for pneumonia (congestive pneumonia).

In rare cases, other inflammations (for example, bone inflammation) may also be responsible for pneumonia by carrying the pathogens to the lungs through the bloodstream.

The risk group includes:

  • Elderly and weakened people
  • Chronically ill people and here mainly patients with heart disease, bronchitis or diabetes mellitus.
  • People with a weakened immune system (e.g. HIV infection).
  • People suffering from alcoholism
  • Children, and especially chronically ill children (caution is advised, as pneumonia is often mistaken for appendicitis in children).


The symptoms of pneumonia can vary greatly and depend on the general health of the person affected and the pathogen. Characteristics of a classic pneumonia caused by bacteria are:

  • Sudden chills
  • High fever
  • Cough and shortness of breath, in addition, there may be respiratory pain in the chest.
  • At the beginning the cough is dry, after some time there is coughing up of mucus, which may have a green, yellow, brown or rust-colored color.

People suffering from severe pneumonia have very labored and rapid breathing (tachypnea) due to shortness of breath. Lips and fingernails may sometimes turn blue (cyanosis) due to the lack of oxygen. Deep breathing and coughing is often accompanied by pain.

Children also often complain of pain in the lower abdomen, which is why pneumonia is often mistaken for appendicitis.

Pneumonia caused by viruses or parasites is characterized in its early stages by fever or chills. The cough is dry and there is hardly any mucus. Such pneumonia is also called atypical pneumonia.

If the affected person already suffers from other lung diseases, such as asthma or chronic bronchitis, a worsening is usually observed due to pneumonia.


Pneumonia can usually be detected by the course of the disease, as well as a clinical examination. This includes listening to the lungs.

The characteristics of atypical pneumonia are similar to those of a flu-like infection. For this reason, the diagnosis is usually somewhat more difficult. However, a lung X-ray can tell with certainty whether there is an inflammation and what its extent is. Sometimes it is also necessary to do other examinations, such as a computer tomography (CT).

Further information about the cause of pneumonia is provided by bacteriological tests. These look for pathogens in sputum and mucus. In addition, certain elevated values in the blood (such as C-reactive protein or leukocyte count) indicate an inflammation.


People who are ill with pneumonia should definitely observe physical rest and bed rest. Patients should drink plenty of fluids, especially if they are taking mucolytic agents.

Antibiotics are almost always the first-line treatment for pneumonia. Even if the causes are viruses, antibiotics are used. Although this does not stop the viruses, it often causes an additional infection with bacteria (bacterial superinfection), against which antibiotics are effective.

Young people who do not have any other illnesses can usually be treated at home.

If the pneumonia causes severe symptoms or affects large parts of the lungs, treatment in hospital is essential. The same applies to people with immunodeficiency, poor general health, concomitant diseases, as well as complications.


The chances of a complete cure depend on the age of the patient, the type of pathogen, as well as the time of the start of therapy. In young and healthy people, pneumonia usually heals without secondary damage. However, a large proportion of patients still feel tired weeks later and are prone to coughing fits.

The following factors worsen the prognosis:

  • Older age
  • Existing heart or lung diseases (e.g. cardiac insufficiency or chronic bronchitis)
  • Weakened immune system (for example, due to medication or other illnesses)
  • Complications (for example, antibiotic-resistant bacteria)

Patients usually recover from pneumonia, but it should still be considered a serious illness. In industrialized countries, pneumonia is the infectious disease with the highest death rate.

Pneumococcal vaccination offers protection against pneumonia, as pneumococci are often the causative agent of the disease. It is advisable to have all children vaccinated up to the age of 24 months. For older children, adolescents and adults, the vaccination recommendation applies if they suffer from a concomitant disease such as permanent immune deficiency, chronic pneumonia (for example asthma) or a metabolic disease (diabetes mellitus).


Pneumococcal vaccination:

Since July 2006, a vaccination recommendation of the Permanent Vaccination Commission at the Robert Koch Institute (STIKO) for pneumococcal vaccination has been valid for all children up to 24 months of age as basic immunization.

If no vaccination took place as a child, this should be made up for if:

  • The 65th year of life has been exceeded and an infection of the upper respiratory tract occurs frequently.
  • You have a weakened immune system, for example due to congenital immunodeficiencies or an HIV infection.
  • You have a chronic disease, such as chronic bronchitis, coronary heart disease (CHD), heart failure or diabetes mellitus.
  • The spleen has been removed

Flu vaccination:

A vaccination also exists against influenza, which primarily protects the mucous membranes of the respiratory tract from the virus. If the mucous membranes are damaged, the body becomes more susceptible to pneumonia.

The flu vaccination is recommended for the following people:

  • All persons over 60, as the immune system can no longer do its job to the fullest extent after this age.
  • Children and adults suffering from underlying diseases (cardiovascular diseases such as high blood pressure or angina pectoris, lung diseases such as asthma, chronic bronchitis, metabolic diseases such as diabetes mellitus, liver and kidney diseases, organ transplants, HIV infection or leukaemia). All of these diseases can impair the immune system's ability to function properly.
  • Travelers going to Asia should also undergo vaccination. There is a possibility that they will come into contact with poultry (bird flu). Vaccination prevents the human flu virus from merging with the avian flu virus, as a newly formed virus could pose a deadly threat to other people.

If there is no improvement in the cold, or if symptoms such as shortness of breath, coughing or chest pain increase, a doctor should be consulted. If necessary, the doctor should also be informed about any stays abroad in the previous months, as pathogens from other countries sometimes require a different therapy.

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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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