What causes diarrhea


Diarrheal diseases are common. They are usually the result of a virus infection. Prolonged diarrhea requires treatment as it can lead to fluid and salt loss.

At a glance

  • Diarrhea is usually caused by a virus infection, most commonly the highly contagious noroviruses and rotaviruses.
  • Diarrhea is when the stool is very soft or runny at least three times within 24 hours.
  • Acute diarrheal diseases usually last a few days to a week.
  • With diarrhea, the body loses fluids and salts (electrolytes). It is important to make up for this loss.
  • Prolonged diarrhea needs treatment.
  • Some gastrointestinal infections are notifiable diseases.

Note: The information in this article cannot and should not be used as a substitute for a doctor's visit and should not be used for self-diagnosis or self-treatment.

What is diarrheal disease?

Diarrheal diseases are very common. On average, adults in Germany fall ill once a year, children even more often.

Most often, diarrhea is caused by a viral infection. The very contagious noroviruses and rotaviruses are often responsible. A gastrointestinal infection (gastroenteritis) can also be triggered by bacteria such as Salmonella or Campylobacter.

With normal diarrhea, it is usually enough to balance your fluid balance and wait for the infection to pass. Severe or prolonged diarrhea needs treatment. It can lead to dangerous fluid and salt loss. This can be particularly threatening for young children and the elderly.

How do you recognize diarrhea?

A gastrointestinal infection often starts suddenly with gushing vomiting or severe diarrhea. Diarrhea is very soft or runny stool that occurs at least three times in a 24 hour period.

Diarrhea is often accompanied by abdominal pain, cramps and gas. Sometimes there is also a fever, headache and body aches.

Important to know:If the body has lost too much fluids and salts (electrolytes), dizziness and circulation problems can occur. In this case, immediate medical help is required.

A doctor's visit is also advisable if:

  • no improvement after 48 hours
  • high fever
  • Blood in the stool (red or black blood)
  • Mucus deposited on the stool
  • strong pain

What are the causes of diarrhea?

There are many different causes for diarrhea. One of the most common causes is a gastrointestinal infection caused by the highly contagious noroviruses or rotaviruses. Usually small children and older people get sick from it. In Germany, bacterial gastrointestinal infections are mostly caused by Campylobacter or Salmonella. Diarrhea can also occur when traveling. Depending on the travel destination and hygienic conditions, infections with Shigella, certain E. coli bacteria or parasites are responsible.

However, diarrhea is not only caused by infections. Possible other causes are:

  • Unfamiliar food, for example on (long-distance) trips
  • Food intolerance such as gluten or lactose intolerance
  • a "nervous bowel" (irritable bowel syndrome)
  • inflammatory bowel diseases such as Crohn's disease or ulcerative colitis
  • Side effects of certain drugs: They can unbalance the normal intestinal flora and sometimes cause diarrhea. This is especially true for antibiotics.

How does diarrhea work?

Acute diarrhea usually lasts a few days to a week. If the diarrhea lasts longer than two weeks, it is called persistent diarrhea.

How can diarrhea be prevented?

In everyday life, hands often come into contact with viruses and bacteria. The pathogens are transmitted, for example, with stool, vomit, water, food or contaminated objects. To protect yourself and others, washing your hands regularly and thoroughly with soap helps. Hand disinfection can also be useful in acute diarrhea. If there is a second toilet at home, it is helpful if the sick family member can use it alone until they recover.

Garments are best washed at at least 60 degrees. When preparing food, it is important to pay more attention to good hygiene. If you suffer from acute diarrhea, you should not prepare meals for others.

There are a few simple tips to avoid traveler's diarrhea. In subtropical or tropical countries, depending on the hygiene standards, it is advisable to avoid raw, unpeeled fruit and vegetables and not to drink tap water. In the case of fish or meat, make sure that they are well fried or cooked.

The Standing Vaccination Commission (STIKO) recommends vaccination against rotaviruses for infants under 6 months of age. The oral vaccination should protect against infection for about 2 to 3 years.

More detailed information on the subject of diarrhea and how you can prevent the infection can be found at Gesundheitsinformation.de.

How is diarrhea diagnosed?

The doctor will first ask you about the following:

  • whether the symptoms came on suddenly or gradually
  • how long the diarrhea has been going on and how frequent it is
  • what the stool is like (appearance and consistency)
  • whether other symptoms such as abdominal pain, vomiting or fever occur
  • what was eaten before the diarrhea began

The following is also important for the diagnosis:

  • whether you have recently been abroad
  • whether, and if so, which medications were or are being taken
  • whether allergies or intolerances are known
  • whether you have a chronic condition such as diabetes

If you have bloody or persistent diarrhea or diarrhea with mucus deposits, a stool or blood sample may be necessary. In this way it can be determined which pathogens triggered the infection.

How is diarrhea treated?

Diarrhea leads to a loss of fluids and electrolytes. It is important to make up for this loss.

In acute diarrhea, for example, sugared tea in combination with savory biscuits helps. Rice, bananas or rusks are gentle on the stomach and are often recommended for acute diarrhea.

Coffee, fruit juices, lemonades, alcohol and fatty foods also irritate the intestines. It may therefore be better to avoid these foods and drinks for the time being.

In adolescents and adults it is not necessary to give special treatment to acute diarrhea. The situation is different with young children and the elderly, as well as with severe diarrhea. Here it makes sense to compensate for the loss of fluids and electrolytes with a rehydration solution (also called electrolyte / glucose solutions).

They are available in the pharmacy or drugstore as a powder that can be dissolved in water at home. This solution contains salts, minerals and glucose.

If a rehydration solution is not available, for example when traveling, a replacement will also help. The following ingredients are poured into one liter of packaged or boiled water and stirred:

  • 4 teaspoons of sugar
  • ¾ teaspoon table salt
  • a glass of packaged orange juice

In order to shorten the duration of the diarrhea, in addition to fluid intake and other treatments, foods or dietary supplements with probiotic microorganisms (probiotics) can also help.

Depending on the duration and severity of the symptoms, other treatments may also be considered:

  • Drugs like loperamide or racecadotril calm the intestines. You can reduce the number of times you use the toilet. Loperamide is not suitable for children under the age of 12 and Racecadotril requires a prescription for children.
  • Certain yeast tablets (perenterol) are also sometimes recommended. They accelerate the elimination of the pathogens and are intended to support the restoration of the natural intestinal flora. Charcoal tablets are also said to alleviate the symptoms. They are dissolved in water before ingestion. However, there are no meaningful studies that can adequately demonstrate the benefits and harms of these treatment options. Yeast tablets are not suitable for the seriously ill or people with a very weak immune system.
  • Antibiotics only work against bacteria, not viruses. They therefore only help with a bacterial intestinal infection.

What else is important to know?

Reportable diseases also include some gastrointestinal infections. This means that the doctor must notify the local health department. There is an obligation to notify, for example, of a proven infection with noroviruses or rotaviruses, Salmonella or Campylobacter.

A gastrointestinal infection in children under 6 years of age who go to a community facility such as a daycare center or kindergarten is generally notifiable. If an infection is discovered during a visit to the doctor, the doctor must report it to the responsible health department within 24 hours. Only when the sick child has not had diarrhea for 2 days can they go back to the day care center. This will prevent other children from getting sick too.

There is an infection protection law in Germany. Its purpose is to ensure that communicable diseases can be prevented and their spread prevented. According to the law, people who work in food professions and who are suspected of having an intestinal infection, who are sick or have salmonella, are only allowed to work again if no more pathogens can be detected in three stool samples examined. Also in the 4 to 6 weeks afterwards, to be on the safe side, you should pay particular attention to your hand hygiene in the workplace.

In cooperation with the Institute for Quality and Efficiency in Health Care (IQWiG). Was standing: