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Overview: Pneumonia

Last Update: January 14, 2026; Next update: 2029.

Introduction

People who develop pneumonia often feel very ill quite suddenly: They may have a high fever, chills, a cough and get out of breath easily. This happens because small air sacs (alveoli) in their lungs are inflamed, along with the surrounding lung tissue.

Pneumonia is often caused by bacteria. It can then usually be successfully treated with antibiotics. There are also vaccinations that can prevent pneumonia that's caused by certain germs.

People who are otherwise in good health generally recover within a few weeks. But pneumonia shouldn't be taken too lightly: It can take several months to get back to full strength.

Pneumonia may sometimes lead to life-threatening complications, especially if you have already been weakened by another illness. It can also be dangerous in babies and in older age.

At a glance

  • Pneumonia is usually caused by bacteria or viruses.
  • The typical symptoms of pneumonia are a high fever, a cough and feeling weak.
  • If it is caused by bacteria, it is typically treated with antibiotics.
  • Washing your hands frequently and paying attention to good hygiene can prevent infection.
  • Complications are more common in babies, in older age, and in people who also have certain other medical conditions.
  • Vaccinations are recommended for people who have a higher risk.
This simplified anatomical illustration shows pneumonia in the left lung. On the right side of the illustration there is a detailed view of healthy and inflamed alveoli.

Pneumonia in the left lung

Symptoms

The typical signs of pneumonia are:

  • High fever and chills
  • Feeling weak and very unwell
  • Cough with phlegm
  • 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 have certain typical symptoms. Or other, less typical symptoms such as diarrhea, stomach pain or drowsiness and confusion might be more noticeable.

Causes

Pneumonia is often caused by bacteria. Which kind of bacteria generally depends on where you become infected: If you get pneumonia at home, it is likely to be caused by bacteria called pneumococci. If you develop pneumonia in the hospital, it is often caused by other bacteria that are harder to treat.

It can also be caused by viruses or (in rarer cases) fungal infections. Sometimes pneumonia is caused by things other than germs – such as radiation, inhaled poisonous substances, an allergic reaction or circulation problems in the lungs.

Risk factors

The risk of developing pneumonia is particularly high in babies and older people (over 65 years).

Other risk factors include:

Sometimes germs from the mouth and throat, bits of food or stomach contents can get into the airways and lead to pneumonia. This is known as aspiration pneumonia. The risk is especially high in people who are bedridden, confused, or have trouble swallowing due to dementia or stroke, for instance.

Some medications are also thought to possibly increase the risk of pneumonia, such as drugs that reduce the level of acid in the stomach. But it's still not clear whether they actually have this effect.

Prevalence

Over 500,000 people develop pneumonia each year in Germany, and about 250,000 of them need treatment in hospital. A total of 20,000 people die of pneumonia per year – 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.

Pneumonia is even more common in poorer countries, where babies and children are most often affected.

Outlook

The typical signs of pneumonia are a sudden high fever and chills. People with pneumonia 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 also develop gradually and start with few or only mild symptoms, particularly in older people.

Left untreated, the fever lasts for about one week. Your body temperature then goes back down to normal levels. This may 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 is already weak. So complications are common during this phase of the illness.

Once this phase has passed, your general wellbeing gradually improves and the pneumonia usually goes away completely after about four weeks. But you may still feel run-down and tired for some time, and the cough may also last quite a while.

Pneumonia rarely becomes this serious nowadays, though, because it's usually treated immediately. Taking antibiotics usually makes the fever go away more quickly, and helps you to feel better faster. But it's still important not to start doing too much too soon after having pneumonia. Otherwise, it may come back or lead to other complications.

Effects

Pneumonia can cause the membrane that covers the lungs (the pleura) to become inflamed. That results in severe pain when you cough or breathe. Fluid may also collect between the lungs and the chest wall, making it even harder to breathe. Another possible complication is a lung abscess (a pus-filled space in the lung).

Pneumonia can sometimes lead to life-threatening complications, too – such as heart rhythm problems, circulatory collapse, respiratory or heart failure, or blood poisoning (sepsis). The risk of complications is greater if you

  • are under the age of 2 years or over the age of 65,
  • have other diseases, such as heart or kidney disease,
  • have a weakened immune system,
  • caught pneumonia in the hospital, or
  • were already being treated with antibiotics in the months before you developed pneumonia.

Diagnosis

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

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

Blood is taken as well, to measure things like the level of infection. Because the infected lungs are no longer working properly, doctors may need to check how much oxygen is in the blood. That can be done without taking blood, using a technique known as pulse oximetry. This involves placing a clip-like device on one of your fingers. The oxygen content is measured using a light sensor on the device.

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

Prevention

The best way to prevent respiratory infections is by practicing good personal hygiene, including regularly washing your hands and keeping your distance from others.

People who have an increased risk of pneumonia or complications are advised to have vaccines too. For example, children can be vaccinated against Hemophilus influenzae bacteria and pneumococcal bacteria. People over the age of 60 are advised to have the flu vaccine and the pneumococcal vaccine.

Herbal medicines and dietary supplements such as vitamin products are often said to strengthen the immune system. But no studies have proven that they have any worthwhile benefits – except in people who have a diagnosed vitamin deficiency. That is rare in Germany and similar countries nowadays, and generally only occurs in people who have a very unbalanced diet.

Treatment

If pneumonia is caused by bacteria, it is generally treated with antibiotics. The most suitable type of antibiotics will depend on the type of bacteria.

The treatment with antibiotics lasts about 5 to 7 days. They can be taken in the form of tablets or a syrup. Depending on the severity of the illness and the risk of complications, treatment in a hospital may sometimes be needed. The antibiotics are usually given as an infusion (drip) there.

People with severe pneumonia may be given a steroid injection too. Sometimes extra oxygen is given through a mask; artificial respiration is less commonly needed.

If the pneumonia was caused by viruses such as flu viruses or the coronavirus SARS-CoV-2, other medications known as antiviral drugs may be used. These specifically target viruses. Antibiotics are also used in viral pneumonia, though, with the aim of preventing a bacterial infection from developing too.

Cough medicines from the pharmacy, special breathing exercises and physical therapy aren't recommended for the treatment of pneumonia.

Further information

When people are ill or need medical advice, they usually go to see their family doctor first. Information about health care in Germany can help you to navigate the German healthcare system and find a suitable doctor. You can use this list of questions to prepare for your appointment.

Sources

© IQWiG (Institute for Quality and Efficiency in Health Care)
Bookshelf ID: NBK525774
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