Overview

Diarrhea is a symptom characterized by an abnormal increase in stool frequency, liquidity, or weight. Diarrhea may be acute, persistent, or chronic. Many cases of acute diarrhea—defined as symptoms that last <14 days—in children 6 months to 5 years of age can be managed adequately with fluid and electrolyte replacement and dietary interventions.

Children with moderate-to-severe diarrhea, persistent diarrhea (symptoms that last 14 days to 4 weeks), or chronic diarrhea (symptoms that last >4 weeks) require evaluation by a primary care provider.

Treatment with nonprescription antidiarrheal medications is not recommended for children 5 years of age or younger.

Etiology

• Diarrhea is a common symptom of acute gastroenteritis.
  
• Rotavirus is a common causative pathogen in cases of acute gastroenteritis in children ≤5 years of age in the United States. Transmission is by the fecal–oral route; the peak infectious period is during the winter months (November to February).
  
  
  
  • Available rotavirus vaccines prevent 75%–85% of all cases of rotavirus gastroenteritis and 95%–98% of severe infections.
  
  
• Acute gastroenteritis also may be caused by bacteria (especially Campylobacter sp., Salmonella sp., Shigella sp., and Escherichia coli). Protozoa are less frequent causes.
  
• Foodborne transmission of pathogens accounts for 36% of acute gastroenteritis episodes in the United States. Of these infections, 67% are caused by viruses, 30% by bacteria (primarily Salmonella and Campylobacter), and 3% by protozoa.
  
• Travelers’ diarrhea is an acute, secretory diarrhea that usually is acquired through ingestion of contaminated food or water.
  
  
  
  • E. coli is the most common infecting organism in travelers’ diarrhea.
    
  • The causative organisms are found most often on foods such as fruits, vegetables, raw meat, seafood, and even hot sauces. Less commonly, pathogens are found in the local water, including ice cubes.
  
  
• Food intolerance can provoke diarrhea and may result from a food allergy or ingestion of foods that are excessively fatty or spicy, or contain a high amount of dietary fiber or many seeds.
  
• Infants born with lactase deficiency may develop diarrhea if they consume cow milk or milk-based products. Lactase normally hydrolyzes dietary carbohydrates such as lactose and sucrose to monosaccharides. When these carbohydrates are not hydrolyzed, they pool in the lumen of the intestine and produce an osmotic imbalance. The resulting hyperosmolarity draws fluid into the intestinal lumen, causing diarrhea.
  
• Acute diarrhea also may be caused by poisoning, medications, or various acute or chronic illnesses.

Signs and Symptoms

• Signs and symptoms associated with acute infectious diarrheal illness caused by the most common pathogens are shown in Table 1.

Complications

• Fluid and electrolyte imbalance is the major complication of diarrheal illness. Assessment of the patient’s risk for dehydration and the degree of dehydration present is key in determining the appropriateness of self-care and the need for medical referral.
  
  
  
  • The specific signs and symptoms of dehydration are associated with the severity of the diarrhea, as well as the etiology and degree of fluid and electrolyte losses (see Table 2).
  
  
• Children <5 years of age and adults >65 years of age are at greater risk for complications than other patients.
  
• Children ≥2 years of age are most likely to suffer complications that require hospitalization.
  
• In newborns, water may comprise up to 75% of total body weight. Severe diarrhea may cause water loss equal to ≥10% of body weight. After 8–10 bowel movements within a 24-hour period, a 2-month-old infant could lose enough fluid to cause circulatory collapse and renal failure.

TABLE 1. Characteristics of Common Infectious Diarrheal Illnesses

TABLE 2. Assessment of Dehydration and Severity of Acute Diarrhea

^a If signs of dehydration are absent, rehydration therapy is not required. Maintenance therapy and replacement of stool losses should be undertaken.

^b Signs and symptoms experienced especially by young children.

^c Signs and symptoms of concern for young infants.

Treatment

• Uncomplicated cases of mild-to-moderate acute diarrhea with minimal, mild, or moderate dehydration (see Table 2) generally are amenable to self-treatment.
  
• Self-management of acute diarrhea in children ≤5 years of age should focus on correcting fluid losses and electrolyte imbalances by administering commercially available oral rehydration solutions (i.e., dextrose–electrolyte solutions such as Pedialyte or CeraLyte) in adequate doses.
  
• According to the patient’s fluid and electrolyte status, oral treatment may be carried out in two phases: rehydration therapy and maintenance therapy.
  
  
  
  • Rehydration over 3–4 hours quickly replaces water and electrolyte deficits to restore normal body composition.
    
  • In the maintenance phase, electrolyte solutions are given to maintain normal body composition until adequate dietary intake is reestablished.
  
  
• Premixed oral rehydration solutions are preferred for use in children because they are safe and convenient. Improper mixing of dry powders by caregivers has led to patient fluid and electrolyte complications and injury.
  
  
  
  • All available premixed solutions are equally safe and effective; there is no evidence that one product is clinically superior to another in effecting rehydration.
    
  • If a dry powder oral rehydration solution is selected, pharmacists should give parents or caregivers explicit directions for mixing and verify that they understand the directions.
  
  
• Colas, ginger ale, apple juice, sports drinks, tea, chicken broth, and similar fluids are not recommended for oral rehydration therapy in children 6 months to 5 years of age with diarrhea.
  
  
  
  • Tea is inappropriate for children because of its low sodium content.
    
  • Chicken broth is not recommended because of its inappropriately high sodium content.
  
  
• A normal, age-appropriate diet should be reintroduced once the patient has been rehydrated (which should take no longer than 3–4 hours). Patients should not go longer than 24 hours without food.
  
  
  
  • Early refeeding, in combination with maintenance oral rehydration, improves outcomes in children by reducing duration of the diarrhea, reducing stool output, and improving weight gain.
    
  • Most infants and children with acute diarrhea can tolerate full-strength breast milk and cow milk.
    
  • The BRAT diet (bananas, rice, applesauce, and toast) is not recommended. It provides insufficient calories, protein, and fat, especially in situations of strict or prolonged use.
  
  
• Parents should be advised to avoid feeding children fatty foods, foods rich in simple sugars that can cause osmotic diarrhea, and spicy foods that may cause GI upset.

Complementary Therapy

• There is no evidence to substantiate the safety and effectiveness of herbal or homeopathic therapies in the treatment of acute diarrheal diseases. Therefore, their use cannot be recommended.
  
• Convincing evidence suggests that probiotics—including several Lactobacillus species, Bifidobacteria lactis, and Saccharomyces boulardii—are effective in preventing and treating mild cases of acute, uncomplicated diarrhea, especially rotavirus diarrhea in children. The exact mechanisms underlying the effects of these bacteria are not clear.
  
  
  
  • The role of probiotics in bacterial gastroenteritis and moderate-to-severe diarrhea is not supported conclusively by available evidence.

Cautions and Contraindications

• Diarrhea of any severity in infants <6 months of age and moderate-to-severe diarrhea in children ≤2 years of age requires evaluation by a primary care provider.
  
  
  
  • Severe diarrhea constitutes a medical emergency, especially in young children. Patients with severe diarrhea require immediate medical evaluation and treatment with intravenous fluid therapy.
  
  
• Nonprescription loperamide is labeled for use in children >6 years of age. Use in children <6 years is not recommended because loperamide produces only modest, clinically insignificant effects on stool volume and duration of illness, with an unacceptably high risk of side effects (including life-threatening side effects such as ileus and toxic megacolon).
  
• Bismuth subsalicylate is approved for the management of acute diarrhea in children <12 years of age.
  
• The GI adsorbents attapulgite, kaolin, and pectin are no longer used to treat diarrhea.
  
  
  
  • Evidence supporting the safety and effectiveness of attapulgite and pectin is lacking. Products containing these adsorbents have either been reformulated or withdrawn from the market.
    
  • Kaolin is recognized by the Food and Drug Administration as safe and effective, but no single-ingredient kaolin products are currently available in the United States.

Clinical Pearls

• The Centers for Disease Control and Prevention recommend that families with infants keep a supply of oral rehydration solution on hand at home. Early administration of an oral rehydration solution at home is vital if hospitalization is to be avoided.
  
• Patients with lactase deficiency may take lactase enzyme preparations with milk or other dairy products to prevent osmotic diarrhea.

Follow-Up

• Otherwise healthy patients with uncomplicated acute diarrhea usually improve clinically within 24–48 hours. If the condition remains the same or worsens after 48 hours of onset, medical referral is necessary to prevent complications.
  
• Medical referral also is necessary if any of the following signs and symptoms occur during treatment:
  
  
  
  • High fever.
    
  • Stools that contain blood or mucus.
    
  • Signs of worsening dehydration (e.g., low blood pressure, rapid pulse, and mental confusion).

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