What medications are used to treat acute gastroenteritis?

Medications for Acute Gastroenteritis

The cornerstone treatment for acute gastroenteritis is oral rehydration therapy, with medications such as ondansetron for vomiting and loperamide for diarrhea in adults serving as adjunctive treatments, but never as substitutes for proper rehydration. 1, 2

Rehydration (First-Line Treatment)

Oral Rehydration

• Mild to moderate dehydration: Oral rehydration solution (ORS) is the mainstay treatment
  • Reduced osmolarity ORS containing 65-70 mEq/L sodium and 75-90 mmol/L glucose 2
  • Replace ongoing losses: approximately 10 mL/kg for each watery stool 2
  • Continue until clinical dehydration is corrected 1

Intravenous Rehydration

• Indications: Severe dehydration, shock, altered mental status, failure of ORS, or ileus 1
• Solutions: Lactated Ringer's or normal saline 1, 2
• Duration: Continue until pulse, perfusion, and mental status normalize 1

Symptomatic Medications

Antiemetics

• Ondansetron: May be given to children >4 years and adolescents to facilitate tolerance of oral rehydration 1, 2
• Timing: Should only be used after adequate hydration has begun 1

Antimotility Agents

• Loperamide:
  • Adults only: May be given to immunocompetent adults with acute watery diarrhea 1, 2
  • Dosing: 4 mg initial dose, then 2 mg after each loose stool (maximum 16 mg/day) 2, 3
  • Contraindications:
    • Children <18 years of age 1
    • Inflammatory diarrhea or diarrhea with fever 1
    • Cases where toxic megacolon may result 1, 3

Probiotics

• May be offered to reduce symptom severity and duration in immunocompetent adults and children 1, 2
• Specific recommendations for organism selection, delivery route, and dosage should be based on literature searches and manufacturer guidance 1

Zinc Supplementation

• Reduces diarrhea duration in children 6 months to 5 years who:
  • Live in countries with high zinc deficiency prevalence
  • Show signs of malnutrition 1, 2

Antibiotics

• Not routinely indicated for uncomplicated gastroenteritis
• Consider for:
  • Severe diarrhea 2
  • Specific identified pathogens
  • Immunocompromised patients
• First choice: Azithromycin (single dose 500 mg) for empiric treatment 2
• Alternative: Fluoroquinolones where resistance is not a concern 2

Dietary Management

• Continue regular diet with emphasis on starches, cereals, yogurt, fruits, and vegetables 2
• Avoid foods high in simple sugars and fats 2
• Breastfeeding should be continued in infants throughout the diarrheal episode 1, 2
• Formula-fed infants should resume full-strength, lactose-free or lactose-reduced formulas immediately after rehydration 2
• Avoid prolonged use of diluted formulas or restrictive diets like BRAT (bananas, rice, applesauce, toast) 2

Important Caveats

1. Medication is not a substitute for rehydration: Antimotility, antinausea, or antiemetic agents should only be used after adequate hydration 1

2. Loperamide risks:

   • Can cause cardiac adverse reactions including QT/QTc interval prolongation and cardiac arrest 3
   • Associated with paralytic ileus, especially in young children 3

3. Warning signs requiring immediate attention:

   • Bloody diarrhea
   • Persistent vomiting
   • Signs of severe dehydration
   • Altered mental status
   • High fever 2

4. Infection control: Hand hygiene and appropriate use of gloves and gowns are essential to prevent spread 1, 2

The evidence strongly supports that while medications may help manage symptoms, proper rehydration remains the most critical intervention for acute gastroenteritis, with ORS being as effective as IV fluids for preventing hospitalization in most cases 4, 5.