How should viral gastroenteritis be treated, including hydration, diet, antiemetics, antidiarrheals, and indications for intravenous fluids?

Management of Viral Gastroenteritis

Oral rehydration solution (ORS) is the first-line treatment for viral gastroenteritis in all age groups with mild to moderate dehydration, and antimicrobials are not indicated for uncomplicated cases. 1

Hydration Management

Oral Rehydration Therapy (Primary Approach)

• Reduced osmolarity ORS is the cornerstone of treatment for mild to moderate dehydration in infants, children, and adults with acute diarrhea from any cause. 1
• ORS should be initiated immediately based on clinical assessment without waiting for laboratory results, as dehydration poses the main mortality risk. 2
• Continue ORS until clinical dehydration is corrected, then provide maintenance fluids and replace ongoing stool losses until diarrhea and vomiting resolve. 1
• Nasogastric administration of ORS may be considered in patients with moderate dehydration who cannot tolerate oral intake, or in children with normal mental status who are too weak or refuse to drink adequately. 1

Intravenous Fluid Therapy (Reserved for Specific Indications)

• Isotonic intravenous fluids (lactated Ringer's or normal saline) should be administered when there is severe dehydration, shock, altered mental status, failure of ORS therapy, or ileus. 1
• In patients with ketonemia, an initial course of intravenous hydration may be needed to enable tolerance of oral rehydration. 1
• Continue IV rehydration until pulse, perfusion, and mental status normalize, the patient awakens, has no risk factors for aspiration, and has no evidence of ileus. 1
• Once stabilized, the remaining deficit can be replaced using ORS. 1

Nutritional Management

• Continue human milk feeding in infants and children throughout the diarrheal episode. 1
• Resume an age-appropriate usual diet during or immediately after the rehydration process is completed. 1
• Early refeeding decreases intestinal permeability, reduces illness duration, and improves nutritional outcomes. 2
• Most infants can be "fed through" an episode of viral gastroenteritis despite mild lactose intolerance that may persist for 10-14 days following rotavirus infection. 2

Antiemetic Therapy

• Ondansetron may be given to children >4 years of age and adolescents with acute gastroenteritis associated with vomiting to facilitate tolerance of oral rehydration. 1, 2
• This is particularly useful to increase the success rate of oral rehydration therapy and minimize the need for IV therapy and hospitalization. 3
• Antiemetics are not a substitute for fluid and electrolyte therapy but serve as adjuncts once adequate hydration is addressed. 1

Antidiarrheal Agents

Critical Contraindications

• Antimotility drugs (e.g., loperamide) should NOT be given to children <18 years of age with acute diarrhea. 1, 2
• Loperamide should be avoided at any age in suspected or proven cases of inflammatory diarrhea or diarrhea with fever due to risk of toxic megacolon. 1

Limited Adult Use

• Loperamide may be given to immunocompetent adults with acute watery diarrhea only. 1, 2
• This recommendation carries only weak to moderate evidence and should be used judiciously. 1

Adjunctive Therapies

• Probiotic preparations may be offered to reduce symptom severity and duration in immunocompetent adults and children with infectious diarrhea. 1, 2
• Oral zinc supplementation reduces the duration of diarrhea in children 6 months to 5 years of age who reside in countries with high prevalence of zinc deficiency or who have signs of malnutrition. 1, 2
• Bismuth subsalicylate may provide modest symptomatic relief, potentially reducing illness duration by approximately 7 hours. 2, 4

Antimicrobial Therapy (Generally NOT Indicated)

• In most people with acute watery diarrhea without recent international travel, empiric antimicrobial therapy is not recommended. 1
• An exception may be made in immunocompromised patients or young infants who are ill-appearing. 1
• Viral gastroenteritis is self-limited with virus replication restricted to the gut mucosa, making antivirals unnecessary in immunocompetent hosts. 2

Critical Pitfalls to Avoid

• Do not delay ORT waiting for laboratory results—begin rehydration immediately based on clinical assessment. 2, 4
• Do not assume viral etiology if bloody diarrhea is present—this is atypical for viral gastroenteritis and requires investigation for bacterial or other causes. 5, 4
• Do not use antimotility agents in children or in any patient with fever or inflammatory diarrhea, as this increases the risk of complications including toxic megacolon. 1
• Measurements of serum electrolytes, creatinine, and glucose are usually not necessary and should only be considered in children with severe dehydration requiring hospitalization and IV therapy. 3

Red Flags Requiring Further Investigation

• Persistent symptoms beyond the typical gastroenteritis timeline (>1 week) should prompt further investigation. 5
• Signs of severe dehydration including decreased urine output, dry mouth and tongue, sunken eyes, no tears when crying (in children), and unusual drowsiness or lethargy require immediate medical attention. 2
• Bloody diarrhea is not typical of viral gastroenteritis and warrants investigation for alternative etiologies. 5, 4