Definition of diarrhea

Diarrhea is the emission of at least three soft or liquid stools per day, or at an abnormal frequency for a given individual. It is generally the symptom of a gastrointestinal infection, mostly viral.

The infection is transmitted by the consumption of contaminated water or food or, more often than not, from one person to another (human contamination).
Severe diarrhea leads to loss of fluids and sodium (electrolytes) and can be fatal, especially in young children and undernourished or immunodeficient persons.

Abdominal pain and vomiting often come with diarrhea. Moderate fever can also occur.

Diarrhea is said to be acute when it lasts for less than two weeks. In most cases, acute diarrhea comes on suddenly. It generally lasts less than a week, and does not relapse in the short term.

Each year in France, 5% of inhabitants see a general practitioner for acute diarrhea. The Norovirus (most often incriminated) or the Rotavirus in very young children, are likely to lead to packed doctors’ waiting rooms and A&E units, reaching epidemic level in winter.

Diarrhea is hemorrhagic up to one in a hundred cases. Acute diarrhea generally goes away on its own or with symptomatic treatment in less than 5 days. Sick leave is prescribed in one out of three times.


Diarrhea occurs by water and electrolyte hypersecretion, and can come with accelerated intestinal motility. The water in the digestive tract does not therefore have enough time to be reabsorbed, and the stools become soft, or even liquid. A change of diet, while travelling for instance, may cause diarrhea. Some drugs or types of food intolerance can also bring on diarrhea episodes.

Infectious causes
In developed countries, we list around one acute gastrointestinal episode (vomiting and/or diarrhea) per year and per inhabitant. Most last less than 24 hours, and are often mistakenly considered to be food-related, whereas they are mainly of viral origin. A dietary cause should be envisaged in the light of simultaneous cases, especially from meals served in institutional catering. This usually involves brief poisoning from bacterial toxins. It is not necessary to see a doctor unless there is also dehydration.

Iatrogenic causes
Diarrhea can sometimes be caused by taking antibiotics. 10% of patients taking antibiotics see changes in their intestinal transit. Most often, this type of diarrhea is caused by digestive metabolic changes, including a decrease in colonic bacterial flora fermentation ability (dysbiosis). It is benign and goes away when the treatment is stopped.


General treatment
In most cases, general practitioners are called upon in the first 48 hours of onset of the diarrhea. They begin by determining how it occurred and the effects on the general condition, especially the risk of dehydration. Subject to exceptions, they simply need to provide some fluid intake, diet and hygiene recommendations (hand washing, not sharing towels and cutlery, toilet disinfection), and to prescribe a symptomatic treatment.

Symptomatic treatment
The symptomatic treatment of diarrhea consists of making up for water and sodium losses. Rehydration solutions are available in sachets to be dissolved in 200 ml water with low mineral content, and fully balance out loss of liquids (and never use sodas such as colas).
In addition, drugs such as intestinal anti-secretory agents resolve the unpleasant symptoms rapidly, while avoiding secondary constipation.

Most cases of infectious diarrhea, especially viral, resolve spontaneously in less than 5 days, and do not require any additional investigations or treatment.

When acute diarrhea lasts for more than 5 days despite the symptomatic treatment, it is acceptable for these investigations to be considered. Patients are thus prescribed a stool culture and parasitology stool sample test.
Where an intestinal infection from a pathogenic bacterium is identified, antibiotics are prescribed to reduce infection development. Finally, identification of a pathogenic parasite requires specific anti-parasitic treatment.

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