Introduction

Diarrhea is very common: In Germany, for instance, adults get it once a year on average, and it is even more common in children. It is usually caused by viruses, the most common of which are the highly contagious norovirus and rotavirus. Infectious diarrhea can also come from bacteria such as Salmonella or Campylobacter.

In normal cases of diarrhea, you can usually just replace the fluids you lose and wait until the infection goes away. But more severe or longer lasting diarrhea needs to be treated because it can lead to the loss of dangerously high levels of fluid and salt, especially in young children and older people.

At a glance

• Gastrointestinal infections often start with sudden vomiting and diarrhea – soft or liquid bowel movement at least three times within 24 hours.
• Diarrhea is commonly caused by the very contagious noroviruses and rotaviruses.
• It is usually enough to get enough to drink and to wait until the diarrhea goes away after a few days.
• It is a good idea to see a doctor if you feel dizzy, weak or notice other signs of dehydration.

Symptoms

The infection often starts suddenly with projectile vomiting or severe diarrhea. It is considered to be diarrhea if you have more than three very loose or liquid bowel movements within 24 hours. People who have diarrhea often have stomach ache, cramps and bloating too. Diarrhea and nausea are sometimes also accompanied by fever, headache and joint pain.

Dizziness and feeling faint could be signs that your body has lost too much liquid and salts (electrolytes). If that happens, immediate medical attention is needed. Other reasons to seek medical help for diarrhea include:

• No improvement after 48 hours
• High fever
• Blood in your poo (it has red blood in it or is black)
• Mucous coating on the poo
• Severe pain

Causes and risk factors

Diarrhea can have a number of different causes. The most common is an infection arising from the very contagious noroviruses and rotaviruses, which most often affect children and older people. Bacterial diarrhea is usually caused by Campylobacter or Salmonella bacteria. When you travel to places with poor sanitary conditions, infections with Shigella, certain E. coli bacteria and parasites can cause diarrhea too.

Diarrhea can also have other causes besides infections, including the following:

• Food you aren't used to (for example while traveling abroad)
• Food intolerances like gluten or lactose intolerance
• Irritable bowel syndrome (IBS, also called “spastic colon”)
• Chronic inflammatory bowel diseases like Crohn’s disease or ulcerative colitis
• Side effects of medication: Antibiotics in particular sometimes cause diarrhea because they also attack normal gut flora.

Outlook

Acute diarrhea is usually over within a few days or a week. Diarrhea that lasts for more than two weeks is considered to be persistent diarrhea.

Effects

Acute diarrhea is usually harmless. But it's important to seek medical advice if you have severe, watery diarrhea or frequent vomiting with major loss of fluids, in order to prevent circulatory collapse. This is especially true for babies and toddlers, people with weakened immune systems, and older people. Because older people often feel less thirsty, and may not drink enough as a result, they are at greater risk of dehydration (not having enough fluids in the body).

The following could be signs of dehydration:

• Worsening general health
• Sunken eyes, cheeks or face
• Faster breathing or higher pulse than normal
• Less elastic skin: When you pinch some of the skin on the arm or belly and let go, it doesn't immediately bounce back to its original position. Instead, a small visible skin fold remains.
• Extreme thirst, lightheadedness, dark-colored pee or lack of urge to pee, as well as dry eyes or lips, or a dry tongue
• Older people may sometimes have chest pain or muscle cramps too.

Diagnosis

When you see the doctor you will first be asked:

• whether your symptoms started suddenly or gradually,
• what your poo looks like (consistency and appearance),
• how long and how frequently you have had diarrhea,
• whether you also have symptoms such as stomach ache, vomiting or fever, and
• what you had to eat before getting diarrhea.

It is also important for them to know

• whether you have been traveling recently,
• what medications you were or are taking,
• whether you have any diagnosed allergies or intolerances, and
• whether you have a chronic disease, such as diabetes.

If you have bloody or persistent diarrhea, a sample of your stool (poo) or blood may be needed to find out what kind of infection you have. The same applies if there is mucus in the diarrhea.

Prevention

Viruses and bacteria spread through contact with poo, vomit and contaminated objects, water or food. These germs can get onto toilets, door handles or clothing. Indirect infection is possible if you touch a contaminated object with your hand, and then touch your mouth with that hand.

This means that it is very important to frequently wash your hands thoroughly with soap if you have acute diarrhea, in order to protect others from infection. Washing your hands also protects you from infection if someone you know is infected. A hand disinfectant can help too. If you have a second bathroom at home, whoever is ill can be the only one to use it.

Clothes should be washed at temperatures above 60 degrees Celsius (about 140 degrees Fahrenheit) if possible. It is important to pay attention to hygiene in the kitchen and while preparing food. Anyone with acute diarrhea shouldn't prepare food for others if possible. This may be prohibited by law for workers in the food service industry.

When traveling to tropical or subtropical climates, you may need to avoid uncooked, unpeeled fruit and vegetables and not drink tap water. Don't eat undercooked meat or fish.

The German Standing Committee on Vaccination (STIKO) has recommended rotavirus vaccinations for babies under the age of six months. The oral vaccine (given by putting drops in the baby's mouth) is meant to prevent infection for about 2 to 3 years.

Treatment

You lose fluids and electrolytes when you have diarrhea, so it's important to replace them. For acute diarrhea you usually just need something like tea with sugar and some salted crackers. Foods that are gentle on the stomach are recommended too, such as rice, bananas or rusk bread. Some people also avoid coffee, fruit juices, sweet fizzy drinks, alcohol and fatty foods so they don't irritate their bowel even more.

Acute diarrhea doesn't require special treatment in teenagers and adults. But it's a good idea for young children and older people, as well as people with more severe diarrhea, to replace fluids and electrolytes by using oral rehydration salts (electrolyte/glucose solutions) from the pharmacy or drugstore. These are powders containing salts, minerals and glucose that can be dissolved in water. If these solutions aren't available (for instance, while traveling), the following ingredients can be stirred into one liter of bottled or boiled water:

• 4 teaspoons of sugar,
• ¾ teaspoon of table salt and
• one glass of packaged orange juice.

Box

Foods or dietary supplements that have probiotic microorganisms (probiotics) are also sometimes recommended. But studies have shown that they probably can’t make the diarrhea go away faster.

Depending on how severe the symptoms are and how long they last, other treatments may be considered too:

• Medicines like loperamide or racecadotril can help to slow down the activity of the bowel and lower the number of times you need to go to the bathroom. Both of these medications should only be used after consulting a doctor. Racecadotril is prescription-only for children and is not routinely recommended for children under the age of five years.
• Sometimes certain types of yeast tablets (Perenterol) are recommended. These tablets are thought to help the body get rid of the germs faster and to support natural gut flora. Charcoal tablets dissolved in water can also be taken to relieve diarrhea symptoms. But there's a lack of good-quality research in this area so no conclusions can be drawn about the benefits and harms of these treatment options. People who are very ill or have a very weak immune system shouldn't take yeast tablets because it can’t be ruled out that the yeast itself could start an infection.
• Antibiotics are only an option if the infection is bacterial. They can't fight viruses.

Further information

When people are ill or need medical advice, they usually go to see their family doctor first. In our topic "Health care in Germany" you can read about how to find the right doctor – and our list of questions can help you to prepare for your appointment.

Some gastrointestinal infections (“stomach bugs”) are notifiable diseases in Germany. In other words, doctors who diagnose them have to inform the local health authorities. Examples of notifiable gastrointestinal infections include norovirus, rotavirus, salmonella or campylobacter infections.

For children under the age of six years who spend time with other children (day care, preschool), it is generally mandatory to report infectious diarrhea. In other words, doctors who diagnose infectious diarrhea have to report it to the health authorities within 24 hours. Children with diarrhea can only return to day care or school after they have had two days with no diarrhea.

In Germany, the Infection Protection Act (Infektionsschutzgesetz) specifies that people in the food industry should not go to work if they are thought to have infectious diarrhea, if they actually have it, or if they have Salmonella bacteria in their poo. They should only return to work after they have given three stool (poo) samples that weren't found to have diarrhea-causing germs in them. Even then, for the next four to six weeks they should continue to pay particular attention to keeping their hands clean at work, as a precaution.

Sources

• Bundesministerium der Justiz (BMJ), Bundesamt für Justiz (BfJ). Gesetz zur Verhütung und Bekämpfung von Infektionskrankheiten beim Menschen (Infektionsschutzgesetz – IfSG). 2022.
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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. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

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