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Diarrhea in Children


Deborah M. Consolini

, MD, Sidney Kimmel Medical College of Thomas Jefferson University

Last full review/revision Jun 2020| Content last modified Jun 2020
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Diarrhea is frequent loose or watery bowel movements that deviate from a child’s normal pattern.

Diarrhea may be accompanied by anorexia, vomiting, acute weight loss, abdominal pain, fever, or passage of blood. If diarrhea is severe or prolonged, dehydration is likely. Even in the absence of dehydration, chronic diarrhea usually results in weight loss or failure to gain weight.

Diarrhea is a very common pediatric concern, and diarrhea and dehydration cause about 1.5 to 2.5 million deaths/year worldwide. It accounts for about 9% of hospitalizations in the US among children < 5 years of age.

Diarrhea in adults is discussed elsewhere.

Pathophysiology of Diarrhea in Children

Mechanisms of diarrhea may include the following:

  • Osmotic

  • Secretory

  • Inflammatory

  • Malabsorptive

Osmotic diarrhea results from the presence of nonabsorbable solutes in the gastrointestinal tract, as with lactose intolerance. Fasting for 2 to 3 days stops osmotic diarrhea.

Secretory diarrhea results from substances (eg, bacterial toxins) that increase secretion of chloride ions and water into the intestinal lumen. Secretory diarrhea does not stop with fasting.

Inflammatory diarrhea is associated with conditions that cause inflammation or ulceration of the intestinal mucosa (eg, Crohn disease, ulcerative colitis). The resultant outpouring of plasma, serum proteins, blood, and mucous increases fecal bulk and fluid content.

Malabsorption may result from osmotic or secretory mechanisms or conditions that lead to less surface area in the bowel. Conditions such as pancreatic insufficiency and short bowel syndrome and conditions that speed up transit time cause diarrhea due to decreased absorption.

Etiology of Diarrhea in Children

The causes and significance of diarrhea (see Table: Some Causes of Diarrhea) differ depending on whether it is acute (< 2 weeks) or chronic (> 2 weeks). Most cases of diarrhea are acute.

Acute diarrhea usually is caused by

Most gastroenteritis is caused by a virus; however, any enteric pathogen can cause acute diarrhea.

Chronic diarrhea usually is caused by

Chronic diarrhea can also be caused by anatomic disorders and disorders that interfere with absorption or digestion.


Some Causes of Diarrhea


Suggestive Findings

Diagnostic Approach


Antibiotics (eg, broad-spectrum antibiotics, multiple concomitant antibiotics)

Temporal relationship of onset of diarrhea with taking of antibiotics

Clinical evaluation

Bacteria (eg, Campylobacter species, Clostridioides difficile (formerly Clostridium difficile), Escherichia coli [can cause hemolytic-uremic syndrome], Salmonella species, Shigella species, Yersinia enterocolitica)*

Fever, bloody stool, abdominal pain

Possibly petechiae or pallor (in patients with hemolytic uremic syndrome)

History of contact with animals (E. coli) or reptiles (Salmonella)

History of eating undercooked food (Salmonella)

Recent (< 2 months) antibiotic use (C. difficile)

Day care center outbreak

Stool culture

Fecal leukocytes

If patients appear ill, complete blood count, renal function tests, and blood culture

If patient has recently been given antibiotics, stool testing for C. difficile toxin

Food allergy or food poisoning

Allergy: Urticarial rash, lip swelling, abdominal pain, vomiting, diarrhea, difficulty breathing within minutes to several hours after eating

Poisoning: Nausea, vomiting, abdominal pain, diarrhea several hours after ingestion of contaminated food

Clinical evaluation

Parasites (eg, Giardia intestinalis [lamblia], Cryptosporidium parvum)*

Abdominal bloating and cramping, foul-smelling stools, anorexia

Possibly history of travel, use of contaminated water source

Microscopic examination of stool for ova and parasites

Stool antigen tests

Viruses (eg, astrovirus, calicivirus, enteric adenovirus, rotavirus)*

< 5 days of diarrhea with no blood

Often vomiting

Possibly fever

Contact with infected people

Appropriate season for the infection

Clinical evaluation


Delayed passage of stool > 48 hours after birth

Possibly long-standing history of constipation

Bilious vomiting, abdominal distention, ill appearance

Abdominal x-ray

Barium enema

Rectal biopsy

History of bowel resection (eg, for necrotizing enterocolitis, volvulus, or Hirschsprung disease)

Clinical evaluation

Abdominal bloating, flatus, explosive diarrhea

Diarrhea after ingestion of dairy products

Clinical evaluation

Sometimes hydrogen breath test

Sometimes test for reducing substances in stool (to check for carbohydrates) and stool pH (< 6.0 indicates carbohydrates in stool)

Cow's milk protein intolerance (milk protein allergy)


Diarrhea or constipation


Anal fissures

Failure to thrive

Symptom resolution when cow's milk protein is eliminated

Sometimes endoscopy or colonoscopy

Excessive juice intake

History of excessive juice or sugary drink intake (4–6 oz/day)

Clinical evaluation

Chronic nonspecific diarrhea of childhood (toddler's diarrhea)

Age 6 months–5 years

3–10 loose stools/day typically during the day while awake and sometimes immediately after eating

Sometimes undigested food visible in stool

Normal growth, weight gain, activity, and appetite

Clinical evaluation

Immunodeficiency (eg, HIV infection, IgA deficiency, or IgG deficiency)

History of recurrent skin, respiratory tract, or intestinal infections

Weight loss or poor weight gain

HIV test

Complete blood count

Immunoglobulin levels

Bloody stools, crampy abdominal pain, weight loss, anorexia

Possibly arthritis, oral ulcerations, skin lesions, rectal fissures


Eosinophilic gastroenteritis

Abdominal pain, nausea, vomiting, weight loss

Complete blood count for peripheral blood eosinophilia

Sometimes IgE level

Endoscopy and/or colonoscopy

Celiac disease (gluten enteropathy)

Symptom onset after introduction of wheat into diet (typically after age 4–6 months)

Failure to thrive

Recurrent abdominal pain


Diarrhea or constipation

Complete blood count

Serologic screening for celiac disease (IgA antibody to tissue transglutaminase)

Endoscopy for duodenal biopsy

Failure to thrive

Repeated episodes of pneumonia or wheezing

Fatty and foul-smelling stools

Bloating, flatus

72-Hour fecal fat excretion

Sweat test

Genetic testing

Sometimes psoriasiform rash, angular stomatitis

Zinc levels

History of hard stools

Fecal incontinence

Abdominal x-ray

* Can also cause chronic diarrhea.

Evaluation of Diarrhea in Children


History of present illness focuses on quality, frequency, and duration of stools, as well as on any accompanying fever, vomiting, abdominal pain, or blood in the stool. Parents are asked about current or recent (within 2 months) antibiotic use. Clinicians should establish elements of the diet (eg, amounts of juice, foods high in sugars or sorbitol). Any history of hard stools or constipation should be noted. Clinicians should also assess risk factors for infection (eg, recent travel; exposure to questionable food sources; recent contact with animals at a petting zoo, reptiles, or someone with similar symptoms).

Review of systems should seek symptoms of both complications and causes of diarrhea. Symptoms of complications include weight loss and decreased frequency of urination and fluid intake (dehydration). Symptoms of causes include urticarial rash associated with food intake (food allergy); nasal polyps, sinusitis, and poor growth (cystic fibrosis); and arthritis, skin lesions, and anal fissures (inflammatory bowel disease).

Past medical history should assess known causative disorders (eg, immunocompromise, cystic fibrosis, celiac disease, inflammatory bowel disease) in the patient and family members.

Physical examination

Vital signs should be reviewed for indications of dehydration (eg, tachycardia, hypotension) and fever.

General assessment includes checking for signs of lethargy or distress. Growth parameters should be noted.

Because the abdominal examination may elicit discomfort, it is advisable to begin the examination with the head. Examination should focus on the mucous membranes to assess whether they are moist or dry. Nasal polyps; psoriasiform dermatitis around the eyes, nose, and mouth; and oral ulcerations should be noted.

Examination of the extremities focuses on skin turgor, capillary refill time, and the presence of petechiae, purpura, other skin lesions (eg, erythema nodosum, pyoderma gangrenosum), rashes, and erythematous, swollen joints.

Abdominal examination focuses on distention, tenderness, and quality of bowel sounds (eg, high-pitched, normal, absent). Examination of the genitals focuses on presence of rashes and signs of anal fissures or ulcerative lesions.

Red flags

The following findings are of particular concern:

  • Tachycardia, hypotension, and lethargy (significant dehydration)

  • Bloody stools

  • Bilious vomiting

  • Extreme abdominal tenderness and/or distention

  • Petechiae and/or pallor

Interpretation of findings

Antibiotic-related, postinfectious, and anatomic-related causes of diarrhea are typically clear from the history. Determination of the time frame helps establish whether diarrhea is acute or chronic. Establishing the level of acuity is also important. Most cases of acute diarrhea have a viral etiology, are low acuity, and cause fever and nonbloody diarrhea. However, bacterial diarrhea can lead to serious consequences; manifestations include fever, bloody diarrhea, and possibly a petechial or purpuric rash.

Symptoms associated with chronic diarrhea can vary and those of different conditions can overlap. For example, Crohn disease and celiac disease can cause oral ulcerations, a number of conditions can cause rashes, and any condition can lead to a poor growth pattern. If the cause is unclear, further tests are done based on clinical findings (see Table: Some Causes of Diarrhea).


Testing is unnecessary in most cases of acute self-limited diarrhea. However, if the evaluation suggests an etiology other than viral gastroenteritis, testing should be directed by the suspected etiology (see Table: Some Causes of Diarrhea).

Treatment of Diarrhea in Children

Specific causes of diarrhea are treated (eg, gluten-free diet for children with celiac disease).

General treatment focuses on hydration, which can usually be done orally. IV hydration is rarely essential. (CAUTION: Antidiarrheal drugs [eg, loperamide] are not recommended for infants and young children.)


Oral rehydration solution (ORS) should contain complex carbohydrate or 2% glucose and 50 to 90 mEq/L (50 to 90 mmol/L) sodium. Sports drinks, sodas, juices, and similar drinks do not meet these criteria and should not be used. They generally have too little sodium and too much carbohydrate to take advantage of sodium/glucose cotransport, and the osmotic effect of the excess carbohydrate may result in additional fluid loss.

ORS is recommended by the World Health Organization and is widely available in the US without a prescription. Premixed solutions are also available at most pharmacies and supermarkets.

If the child is also vomiting, small, frequent amounts are used, starting with 5 mL every 5 minutes and increasing gradually as tolerated (see Oral Rehydration). If the child is not vomiting, the initial amount is not restricted. In either case, generally 50 mL/kg is given over 4 hours for mild dehydration, and 100 mL/kg is given over 4 hours for moderate dehydration. For each diarrheal stool, an additional 10 mL/kg (up to 240 mL) is given. After 4 hours, the patient is reassessed. If signs of dehydration persist, the same volume is repeated.

Diet and nutrition

Children with an acute diarrheal illness should eat an age-appropriate diet as soon as they have been rehydrated and are not vomiting. Infants may resume breast milk or formula.

For chronic nonspecific diarrhea of childhood (toddler's diarrhea), dietary fat and fiber should be increased, and fluid intake (especially fruit juices) should be decreased.

For other causes of chronic diarrhea, adequate nutrition must be maintained, particularly of fat-soluble vitamins.

Key Points

  • Diarrhea is a common pediatric concern.

  • Gastroenteritis is the most common cause.

  • Testing is rarely necessary in children with acute diarrheal illnesses.

  • Dehydration is likely if diarrhea is severe or prolonged.

  • Oral rehydration is effective in most cases.

  • Antidiarrheal drugs (eg, loperamide) are not recommended for infants and young children.

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