What is Diarrhea?

The term diarrhea (also spelled diarrhoea) refers to passage of loose, watery stools. The usual frequency of passing loose stools or watery stools in cases of diarrhea is at least three or more times a day.

Acute and chronic diarrhea

Acute diarrhea lasts a day or two and usually resolves on its own. Diarrhea lasting more than 2 days may indicate a deeper pathology.

Chronic diarrhea indicates presence of diarrhea for at least 4 weeks. This usually indicates a systemic disease.

Chronic diarrhea may again be continued without relenting or may come and go with periods of normal stools and periods of diarrhea.

Problems with diarrhea

Diarrhea due to any cause or for any duration may cause dehydration. This means that the body loses fluid and electrolytes with numerous episodes of loose watery stools.

Normally most of the water that comes into the intestines is absorbed right back to give the solid or semi solid consistency of the stools.

When there are loose stools there is an inability of the intestines to absorb the water as well as the electrolytes (like salts including sodium, potassium, and chloride) and these are lost in stools.

Loose stools contain more fluids and electrolytes and weigh more than solid stools.

Who does diarrhea affect?

Diarrhea can affect persons of all ages. However, the dehydration caused by severe diarrhea is something that can affect infants, children and the elderly more severely.

Severe dehydration in these extremes of ages may be life threatening if not corrected urgently.

In the United States every adult has at least 1 episode of diarrhea annually while young children have an average of two episodes of acute diarrhea in a year.

Causes of diarrhea

The causes of acute and chronic diarrhea are different. Acute diarrhea is caused by infections by bacteria, viruses or parasites while chronic diarrhea is usually related to a functional disorder such as irritable bowel syndrome or an intestinal disease such as Crohn’s disease.

Common organisms that may cause acute bacterial diarrhea include bacteria like Campylobacter, Salmonella, Shigella, and Escherichia coli (E. coli); viruses like rotavirus, norovirus, cytomegalovirus, herpes simplex virus etc. and parasites like Giardia lamblia, Entamoeba histolytica, and Cryptosporidium.

Food intolerance, allergic reactions to certain medications, medication side effects etc. may also give rise to diarrhea.

Traveller’s diarrhea usually affects tourists and visitors to developing countries in Africa, Asia, Latin America, and the Caribbean. This is usually caused by eating food or drinking water contaminated with bacteria, viruses, or parasites.

Diagnosis of diarrhea

Diagnosis of diarrhea and its cause may be needed if it does not subside in a day or two.

Stool is examined in the laboratory for presence of causative organisms. Several laboratory and imaging studies may be used to diagnose more chronic causes of diarrhea.

Treating diarrhea

The first step to treating diarrhea is replenishing the lost fluids and electrolytes and correcting dehydration.

Although drinking plenty of water is important in preventing dehydration, water does not contain electrolytes. Fruit juices, caffeine-free soft drinks, sports drinks and broths may help adults prevent dehydration.

The choice of drink for children however is the oral rehydration solution prescribed by the World Health Organization (WHO). This replenishes both the water and electrolytes in adequate amounts.

Continuing a healthy and nutritious diet and breast feeding (in case of young breastfeeding children) helps recovery and prevents malnutrition due to prolonged diarrhea.

Further Reading

Last Updated: Jun 5, 2019

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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