What is the recommended treatment for acute diarrhea in patients of all ages?

Treatment of Acute Diarrhea Across All Ages

Oral rehydration solution (ORS) is the cornerstone of treatment for diarrhea in all age groups, with specific volumes and rates determined by dehydration severity; antimotility agents like loperamide are absolutely contraindicated in children under 18 years and should be avoided in adults with bloody diarrhea. 1, 2

Immediate Assessment of Dehydration Severity

Evaluate dehydration by examining skin turgor, mucous membranes, mental status, pulse, and capillary refill time 2, 3:

• Mild dehydration (3-5% fluid deficit): Slightly dry mucous membranes, normal mental status 2
• Moderate dehydration (6-9% fluid deficit): Sunken eyes, decreased skin turgor, tachycardia 2
• Severe dehydration (≥10% fluid deficit): Lethargy, altered consciousness, weak pulse, poor perfusion—this is a medical emergency 1, 2

Rehydration Protocol by Age and Severity

Infants and Children (<18 years)

Mild to Moderate Dehydration:

• Administer 50-100 mL/kg of reduced-osmolarity ORS (75-90 mEq/L sodium) over 2-4 hours 1, 2
• For vomiting children, give 5 mL of ORS every 1-2 minutes using a spoon or syringe, gradually increasing volume as tolerated 2, 3
• If oral intake fails despite small-volume technique, consider nasogastric administration of ORS 1, 2

Severe Dehydration:

• Immediately administer 20 mL/kg IV boluses of lactated Ringer's or normal saline until pulse, perfusion, and mental status normalize 1, 2
• Malnourished infants may benefit from smaller 10 mL/kg boluses due to reduced cardiac capacity 1
• Once stabilized, transition to ORS to complete remaining fluid deficit 1, 2

Ongoing Loss Replacement:

• Replace 10 mL/kg of ORS for each watery stool 2, 3
• Replace 2 mL/kg of ORS for each vomiting episode 2, 3

Adults and Adolescents (≥30 kg)

Mild to Moderate Dehydration:

• Administer 2-4 liters of ORS over 3-4 hours 1
• Replace ongoing losses ad libitum, up to 2 L/day 1

Severe Dehydration:

• IV isotonic crystalloid boluses per standard resuscitation guidelines until vital signs and mental status normalize 1
• Adjust electrolytes based on laboratory values 1

Nutritional Management

Infants

• Continue breastfeeding on demand throughout the entire diarrheal episode without interruption 2, 3
• Resume full-strength formula immediately after rehydration (lactose-containing formula is tolerated in most cases) 1, 2

Children and Adults

• Resume age-appropriate diet during or immediately after rehydration 1, 2
• Recommended foods: starches, cereals, yogurt, fruits, vegetables 2
• Avoid foods high in simple sugars and fats 2

Adjunctive Therapies

Zinc Supplementation

• Administer to children 6 months to 5 years of age, particularly those with malnutrition or in zinc-deficient regions 2, 3
• Reduces diarrhea duration 2

Probiotics

• May be offered to immunocompetent children to reduce symptom severity and duration 2, 4

Ondansetron (for vomiting)

• May be given to children >4 years of age only after adequate hydration is achieved 2
• Facilitates oral rehydration and reduces need for IV therapy 2
• Contraindicated in children <4 years 2, 3

Medications to AVOID

Antimotility Agents (Loperamide)

• Absolutely contraindicated in all children <18 years of age 2, 4, 5
• Contraindicated in adults with bloody diarrhea, fever, or risk of toxic megacolon 2, 5
• In adults with uncomplicated watery diarrhea, loperamide may be used: initial dose 4 mg followed by 2 mg after each unformed stool, maximum 16 mg/day 5, 6

Inappropriate Fluids

• Do NOT use sports drinks, fruit juices, apple juice, or soft drinks for rehydration—they contain inadequate sodium and excessive sugar, worsening osmotic diarrhea 2, 3

Antibiotic Indications

Antibiotics are not routinely indicated for acute watery diarrhea 1, 2. Consider antibiotics only when:

• Bloody diarrhea (dysentery) with fever is present 2
• Watery diarrhea persists >5 days 2
• Patient is immunocompromised with severe illness 2
• Signs of sepsis or enteric fever are present 2

Azithromycin is the preferred empiric antibiotic for dysentery in both adults and children 2

Critical contraindication: Never give antibiotics for suspected STEC O157 (Shiga toxin-producing E. coli), as this increases risk of hemolytic uremic syndrome 2

Warning Signs Requiring Immediate Medical Attention

• Lethargy or altered consciousness 2
• Severe dehydration with shock 2
• Intractable vomiting preventing oral rehydration 2
• High stool output (>10 mL/kg/hour) 2
• Bloody diarrhea with high fever 2
• Decreased urine output 2

Common Pitfalls to Avoid

• Allowing a thirsty child to drink large volumes of ORS ad libitum, which worsens vomiting 2
• Delaying rehydration while awaiting stool culture results 2
• Using homemade rehydration solutions with incorrect electrolyte concentrations 2
• Prescribing antibiotics empirically for non-bloody diarrhea in immunocompetent patients 2
• Unnecessarily restricting diet or prolonging fasting, which worsens nutritional status 4