What is the initial management and treatment approach for acute diarrhea?

Acute Diarrhea Work-Up and Management

Initial Assessment

The cornerstone of acute diarrhea management is clinical assessment of hydration status and oral rehydration therapy, not routine laboratory testing or antibiotics. 1

Clinical Evaluation of Dehydration

Assess hydration status using these specific clinical signs:

• Mild dehydration (3-5% fluid deficit): Increased thirst, slightly dry mucous membranes 1
• Moderate dehydration (6-9% fluid deficit): Loss of skin turgor, skin tenting when pinched, dry mucous membranes 1
• Severe dehydration (≥10% fluid deficit): Severe lethargy or altered consciousness, prolonged skin tenting (>2 seconds), cool and poorly perfused extremities, decreased capillary refill, rapid deep breathing (acidosis) 1

Key clinical pearl: Prolonged skin retraction time, decreased perfusion, and rapid deep breathing are more reliable predictors of dehydration than sunken fontanelle or absence of tears 1

When to Order Laboratory Studies

Laboratory studies are rarely needed for acute diarrhea. 1

Order testing only in these specific situations:

• Stool cultures: Only for dysentery (bloody diarrhea), NOT for routine acute watery diarrhea in immunocompetent patients 1
• Serum electrolytes: Only when clinical signs suggest abnormal sodium or potassium concentrations 1
• Extended workup: Reserved for severe dehydration/illness, persistent fever, bloody stool, immunosuppression, suspected nosocomial infection, or outbreak 1

---

Treatment Algorithm

Step 1: Rehydration Based on Severity

For patients WITHOUT dehydration: Skip rehydration phase and start maintenance therapy immediately 1

For MILD dehydration (3-5% deficit):

• Administer 50 mL/kg of oral rehydration solution (ORS) over 2-4 hours 1, 2
• Use small volumes initially (one teaspoon) via spoon, syringe, or medicine dropper, then gradually increase 1
• Reassess hydration status after 2-4 hours 1

For MODERATE dehydration (6-9% deficit):

• Administer 100 mL/kg of ORS over 2-4 hours using same technique as mild dehydration 1, 2

For SEVERE dehydration (≥10% deficit, shock, or near-shock):

• This is a medical emergency 1
• Immediate IV rehydration with isotonic fluids (Ringer's lactate or normal saline) 1, 2
• Give 20 mL/kg boluses until pulse, perfusion, and mental status normalize 1
• May require two IV lines or alternate access (venous cutdown, femoral vein, intraosseous) 1
• Once consciousness returns, transition remaining deficit to oral rehydration 1

Step 2: Replace Ongoing Losses

During both rehydration and maintenance phases, replace ongoing losses: 1, 2

• 10 mL/kg of ORS for each watery/loose stool 1, 2
• 2 mL/kg of ORS for each vomiting episode 1, 2

Step 3: Nutritional Management

Continue normal feeding throughout the diarrheal episode—do not withhold food. 1

• Breastfed infants: Continue nursing on demand 1, 2
• Bottle-fed infants: Resume full-strength formula immediately after rehydration (lactose-free or lactose-reduced preferred) 1
• Older children: Continue usual diet with starches, cereals, yogurt, fruits, vegetables; avoid foods high in simple sugars and fats 1
• Resume age-appropriate diet during or immediately after rehydration 1, 2

---

Special Situations

Managing Vomiting

Do not abandon oral rehydration due to vomiting—over 90% can be successfully rehydrated orally. 1, 2

• Administer small volumes (5-10 mL) every 1-2 minutes 1, 2
• Use spoon, syringe, cup, or feeding bottle—NOT ad libitum drinking from a cup 1, 2
• Common pitfall: Allowing thirsty child to drink large volumes worsens vomiting 2
• Consider nasogastric ORS administration if oral intake fails 1
• Ondansetron may be used in children >4 years after adequate hydration to facilitate oral rehydration 2

When Antibiotics Are Indicated

Antibiotics are NOT routinely indicated for acute diarrhea. 1

Consider antibiotics only when:

• Dysentery (bloody diarrhea) or high fever present 1
• Watery diarrhea persists >5 days 1
• Stool cultures/microscopy indicate treatable pathogen 1
• Patient is immunocompromised or ill-appearing young infant 1
• Suspected enteric fever with sepsis (after cultures obtained) 1

Critical warning: Avoid antibiotics for STEC O157 and other Shiga toxin 2-producing E. coli 1

Antimotility Agents

Loperamide is contraindicated in children <18 years of age. 1, 2, 3

• Adults: Loperamide may be used for acute watery diarrhea (initial 4 mg, then 2 mg after each unformed stool, maximum 16 mg/day) 1, 3
• Avoid in bloody diarrhea at any age 1
• Not a substitute for fluid and electrolyte therapy 1

---

Red Flags Requiring Immediate Attention

• Bloody diarrhea (dysentery): May require antimicrobial treatment 1, 2
• Severe dehydration with shock: Medical emergency requiring immediate IV access 1, 2
• Intractable vomiting preventing oral rehydration: Consider IV or nasogastric route 1, 2
• High stool output (>10 mL/kg/hour): Higher risk of ORT failure 1, 2
• Signs of glucose malabsorption: Dramatic increase in stool output with ORS administration 1, 2