What is the initial approach for treating diarrhea?

Initial Approach for Treating Diarrhea

The cornerstone of initial diarrhea management is oral rehydration solution (ORS) for mild to moderate dehydration, with immediate escalation to intravenous fluids only for severe dehydration, shock, or altered mental status. 1

Immediate Assessment

Begin by rapidly evaluating hydration status through:

• Vital signs: Check pulse rate, blood pressure (including orthostatic changes), capillary refill time, and mental status 2
• Physical examination: Assess skin turgor, mucous membrane moisture, urine output, and overall perfusion 2
• Severity classification: Mild dehydration (3-5% fluid deficit), moderate (6-9%), or severe (≥10%) 2

Rehydration Protocol

For Mild to Moderate Dehydration

Administer reduced osmolarity ORS (containing 50-90 mEq/L sodium) as first-line therapy 1, 3:

• Mild dehydration: 50 mL/kg over 2-4 hours 2
• Moderate dehydration: 100 mL/kg over 2-4 hours 2
• Continue ORS until clinical dehydration is corrected 1
• Replace ongoing stool losses volume-for-volume with ORS until diarrhea resolves 1

Alternative route: Nasogastric administration may be used for moderate dehydration when patients cannot tolerate oral intake or are too weak to drink adequately 1

For Severe Dehydration

Immediately initiate intravenous rehydration with isotonic fluids 1:

• Administer lactated Ringer's solution or normal saline in 20 mL/kg boluses 2
• Continue IV fluids until pulse, perfusion, and mental status normalize 1
• Once stabilized, transition to ORS for remaining deficit replacement 1

Nutritional Management

Resume feeding immediately after rehydration is complete or even during the rehydration process 1, 3:

• Continue breastfeeding throughout the diarrheal episode in infants 1, 3
• Return to age-appropriate usual diet without delay 1, 3
• Eliminate lactose-containing products temporarily 1

Antimicrobial Therapy Decision

In most patients with acute watery diarrhea without recent international travel, do NOT give empiric antimicrobial therapy 1, 3:

Exceptions Where Empiric Antibiotics May Be Considered:

• Immunocompromised patients with severe illness 1
• Ill-appearing young infants 1
• Clinical features of sepsis with suspected enteric fever 1

Critical Contraindication:

Avoid antibiotics entirely for STEC O157 and other Shiga toxin 2-producing E. coli infections, as antimicrobials increase risk of hemolytic uremic syndrome 1, 3

Adjunctive Medications

Antimotility Agents (Loperamide)

May be given to immunocompetent adults with acute watery diarrhea ONLY after adequate hydration 1, 3:

• Initial dose: 4 mg, followed by 2 mg after each unformed stool (maximum 16 mg/day) 4

Absolute contraindications 1, 3, 4:

• Children under 18 years of age 1
• Bloody diarrhea or mucous in stools 2, 3
• Fever present 1
• Suspected inflammatory diarrhea 1
• Risk of toxic megacolon 1

Antiemetics

Ondansetron may be administered to facilitate oral rehydration tolerance in patients with significant vomiting 1, 3

Critical Pitfalls to Avoid

• Never use antimotility agents as a substitute for fluid and electrolyte therapy—they are ancillary only 1, 3
• Never treat asymptomatic contacts—advise infection control measures instead 1, 3
• Never use commercial sports drinks or fruit juices for rehydration—they have inappropriate electrolyte composition 3
• Never give antibiotics for persistent watery diarrhea lasting ≥14 days without specific pathogen identification 1

Red Flags Requiring Immediate Escalation

Seek urgent evaluation or hospitalization for 2, 5:

• Severe dehydration with altered mental status or shock 1, 2
• Bloody stools with fever 5
• Persistent high fever suggesting invasive bacterial infection 5
• Signs of sepsis 1
• Failure of oral rehydration therapy 1
• Suspected ileus 1