Photo of a man coughing
PantherMedia / Lev Dolgachov

Pneumonia is an inflammation of the air sacs in the lungs () and the surrounding tissue. It often leads to a sudden high fever, the feeling that you are very unwell, a cough and shortness of breath.

Because is usually caused by , it can generally be treated effectively with . Vaccinations that can prevent by certain germs are also available.

People who are otherwise in good health generally recover within a few weeks. But shouldn't be taken too lightly: it can last one or sometimes even several months until you are back to full strength.

Pneumonia may sometimes have life-threatening complications, especially if you have already been weakened by another illness. Pneumonia can also be dangerous for babies and older people.

Image: Pneumonia in the left lung

Pneumonia in the left lung


Typical signs of are:

  • High fever and chills
  • Physical weakness and a strong feeling that you are unwell
  • Cough with phlegm (sputum)
  • Shortness of breath and rapid breathing
  • Racing pulse

The symptoms don't always all occur at the same time. Particularly children and older people may not show some symptoms, or other, less typical symptoms such as diarrhea, stomach pains or drowsiness and confusion might be more noticeable.


Pneumonia is usually caused by bacteria – and most frequently by called pneumococci. Sometimes, other types of such as Haemophilus influenzae or Mycoplasma pneumoniae are also involved. If you develop in the hospital, it's often caused by an of that are harder to treat.

If the airways are already infected by other germs, for example flu viruses, it's easier for the to grow there. This can result in bacterial . It's less common for to be caused by viruses alone. Pneumonia caused by fungi is even rarer. That mainly occurs if the is especially weak, for example due to AIDS.

The germs enter the lungs when tiny droplets of saliva or water are inhaled (droplet ). But people can also become ill because they swallowed the wrong way. Then germs from the mouth and throat, and food residue or material from the stomach can enter the airways and lead to . The medical term for this is aspiration .

Only rarely does a bacterial spread through the bloodstream from elsewhere in the body to the lungs. Pneumonia caused by things besides germs, such as radiation, inhaled poisonous substances, allergic reactions or circulation problems in the lungs, is also rare.

Risk factors

The risk of developing is particularly high in babies and older people (over 65 years). A weakened immune system, for example due to diabetes, kidney problems or cancer, also means that the risk is higher greater. Lung diseases such as and , heart diseases, smoking and certain viral infections such as the flu (influenza) can make people more prone to .

The risk of aspiration is especially high in people who are bedridden  or affected by confusion or difficulties swallowing due to dementia or stroke, for instance.

Some medications are also linked to , such as medicines that reduce the level of acid in the stomach. But it's still not clear whether they actually increase the risk of .


Pneumonia is common, especially in poorer countries. There, infants and children are most often affected.

Over 500,000 people develop each year in Germany, with about 250,000 of them receiving treatment at a hospital. A total of 20,000 people die of , especially older people over 65 and people who have been weakened by other diseases. That makes it one of the top ten causes of death in Germany.


The typical signs of are a sudden high fever and chills. People with start to feel very ill within just a few hours. Symptoms such as a cough with phlegm and shortness of breath are also typical. But it may develop gradually and start with few or only mild symptoms, particularly in older people.

Left untreated, the fever lasts for about one week. Body temperature then goes back down to normal levels. That can also be accompanied by profuse sweating. The blood vessels in the skin also become wider so that the body can give off excess heat. That can put a lot of strain on the heart and circulation of someone who has already been weakened, though. So complications during this phase are not uncommon.

Once this phase has passed, general wellbeing gradually improves and usually subsides completely after about four weeks. But you may still feel run-down and tired for quite a while, and the cough can also be persistent.

Nowadays, though, it's not common for to take this course because it's usually treated immediately. Taking antibiotics usually makes the fever go away more quickly, and helps you to feel better faster. Nevertheless, it's important not to start doing too much too soon after having . Otherwise, it may come back or lead to other complications.


Pneumonia can lead to of the lining that covers the lungs (pulmonary pleura). That causes severe pain when you cough or breathe. Fluid can also collect between the lungs and the chest wall, which makes breathing even more difficult. Another possible complication is a lung abscess, the formation of a pus-filled space in the lung.

Life-threatening complications such as heart rhythm problems, circulatory collapse, respiratory or heart failure, or septicemia are also possible. The risk of complications is greater if you

  • are under 2 years old or over 65,
  • have other diseases such as heart or kidney disease,
  • have a weakened ,
  • need artificial respiration,
  • contracted the disease in a hospital, or
  • were already treated with in the months before you developed .


Pneumonia can often be diagnosed based on its typical symptoms. In a physical examination, the doctor listens carefully to the lungs using a stethoscope and measures your pulse and blood pressure.

An x-ray of the lungs is usually taken, too. The x-ray can show where and how much of the lung tissue is inflamed, for example. A more involved x-ray exam, a CT scan, is sometimes needed. Changes to the outer regions of the lungs can also be seen using ultrasound.

Blood is also taken to measure the level of , for example. Because the inflamed lungs no longer work as well, it may be necessary to check the oxygen content of the blood. That can also be done without taking blood using what is known as pulse oximetry, where a clip with a light sensor is placed onto one of your fingers to optically measure the oxygen content.

Blood, urine and coughed up mucus (phlegm) can be tested in a laboratory to find out exactly which germs caused the .


Generally, practicing personal hygiene, like regularly washing your hands, is the best way to prevent respiratory infections.

Vaccinations are also recommended for people who have an increased risk of or its complications. For example, children can be vaccinated against the Haemophilus influenzae and pneumococci. Flu and pneumococci vaccinations are also suitable for people over 60 years of age.

Herbal medicines and dietary supplements such as vitamin products are often said to strengthen the . But there are, no studies that prove that such substances are worth it – except for people who have a diagnosed vitamin deficiency. That usually only occurs in Germany or similar countries as a result of a very imbalanced diet.


Because the is usually bacterial, is typically treated with antibiotics. The appropriate antibiotic depends on the type of .

Treatment lasts about 5 to 7 days. The antibiotic can be taken as a tablet or syrup. Depending on the severity of the illness and the risk of complications, treatment in a hospital may sometimes be needed. The antibiotic is usually given as an infusion there.

Some people with severe are also given a steroid injection. Inhalation of oxygen using a mask is sometimes necessary; artificial respiration is less commonly needed.

If the was caused by viruses, other drugs are needed, like a virostatic against flu viruses.

Cough medicines from the pharmacy, special breathing exercises or physiotherapy aren't recommended for treating .

Further Information

When people are ill or need medical advice, they usually go to see their family doctor first. Read about how to find the right doctor, how to prepare for the appointment and what to remember.

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IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Created on August 9, 2018
Next planned update: 2021


Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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