What is the treatment for acute diarrhea?

Treatment for Acute Diarrhea

The cornerstone of acute diarrhea management is oral rehydration therapy (ORT) with early refeeding, stratified by the degree of dehydration, with antimotility agents like loperamide reserved for adults with non-bloody diarrhea and antibiotics only for specific bacterial infections.

Initial Assessment

Assess dehydration severity immediately by examining skin turgor, mucous membranes, mental status, pulse, capillary refill, and urine output 1. Measure body weight to establish baseline 1.

Dehydration Categories:

• Mild (3-5% fluid deficit): Slightly dry mucous membranes, normal mental status 1
• Moderate (6-9% fluid deficit): Loss of skin turgor, dry mucous membranes, decreased urine output 1, 2
• Severe (≥10% fluid deficit): Shock or near-shock, altered mental status, absent pulses—this is a medical emergency 1

Identify warning signs requiring immediate medical attention: high fever (>38.5°C), frank blood in stools, severe vomiting preventing oral intake, obvious dehydration, or symptoms in frail elderly (>75 years) 1, 3.

Rehydration Strategy by Severity

No Dehydration

Skip rehydration phase and begin maintenance therapy immediately with increased fluid intake guided by thirst 1. Use glucose-containing drinks (lemonades, fruit juices) or electrolyte-rich soups 1.

Mild Dehydration (3-5% deficit)

Administer 50 mL/kg of oral rehydration solution (ORS) containing 50-90 mEq/L sodium over 2-4 hours 1. Start with small volumes (one teaspoon) using a spoon, syringe, or medicine dropper, then gradually increase as tolerated 1, 2. Reassess after 2-4 hours; if still dehydrated, reestimate deficit and restart 1, 2.

Moderate Dehydration (6-9% deficit)

Administer 100 mL/kg of ORS over 2-4 hours using the same gradual approach 1, 2. Commercial formulations include Pedialyte, CeraLyte, and Enfalac Lytren 2.

Severe Dehydration (≥10% deficit)

Begin IV rehydration immediately with 20 mL/kg boluses of Ringer's lactate or normal saline until pulse, perfusion, and mental status normalize 1. This may require two IV lines or alternate access sites (venous cutdown, femoral vein, intraosseous infusion) 1. Once consciousness returns, switch to oral replacement for remaining deficit 1.

Replacement of Ongoing Losses

Replace ongoing stool and vomit losses continuously during both rehydration and maintenance phases 1:

• 10 mL/kg ORS for each watery/loose stool 1, 2
• 2 mL/kg ORS for each vomiting episode 1, 2
• If losses can be measured accurately: 1 mL ORS per gram of diarrheal stool 1

Dietary Management

Infants and Children

Breastfed infants should continue nursing on demand throughout illness 1, 2. For bottle-fed infants, administer full-strength, lactose-free or lactose-reduced formulas immediately upon rehydration 1. If unavailable, use full-strength lactose-containing formulas under supervision 1. True lactose intolerance (indicated by dramatic worsening of diarrhea with lactose introduction, not just stool-reducing substances) requires temporary lactose removal 1.

Adults

Resume food intake guided by appetite—do not fast 1. Small, light meals are appropriate 1. Avoid fatty, heavy, spicy foods, caffeine (including cola drinks), and lactose-containing foods in prolonged episodes 1, 3. There is no evidence that fasting benefits adults or that solid food hastens or retards recovery 1.

Pharmacological Treatment

Antimotility Agents

Loperamide 2 mg is the drug of choice for adults with non-bloody diarrhea (flexible dosing according to loose bowel movements, maximum 16 mg/day) 1, 3, 4. Avoid loperamide in patients with bloody diarrhea, high fever, or children under 2 years due to risks of toxic megacolon and serious cardiac adverse reactions 4. Loperamide is contraindicated in pediatric patients <2 years due to respiratory depression and cardiac arrest risk 4.

Critical loperamide warnings: Avoid doses higher than recommended due to risk of QT prolongation, Torsades de Pointes, and sudden death 4. Do not combine with QT-prolonging drugs or use in patients with cardiac risk factors 4.

Antibiotics

Reserve antibiotics for specific indications only 1, 5:

• Shigellosis (dysentery): Azithromycin 1000 mg single dose or fluoroquinolones for 3 days 6
• Cholera: Antibiotics beneficial 5
• Traveler's diarrhea (moderate-severe): Azithromycin 500 mg single dose for watery diarrhea or 1000 mg for febrile/bloody diarrhea 6
• Campylobacteriosis: Azithromycin preferred due to fluoroquinolone resistance 6

Do not use antibiotics empirically for routine acute diarrhea 5, 7. For travelers, empirical antimicrobials can be justified during travel abroad based on prior medical advice, especially with fever or bloody stools 1.

Probiotics

Probiotics may shorten illness duration but are not recommended for early treatment due to limited availability and insufficient evidence for routine use 1, 7.

Special Populations

Elderly (>75 years)

Elderly patients require medical supervision rather than self-medication due to higher risk of rapid dehydration, electrolyte imbalances, renal decline, and malnutrition 3. Consider fecal impaction (overflow diarrhea) and C. difficile infection in recently hospitalized patients 3. Seek medical care if no improvement after 48 hours or if warning signs develop 3.

Vomiting Patients

Over 90% of vomiting patients can be successfully rehydrated orally when small volumes (5-10 mL) are given every 1-2 minutes with gradual increases 1. Common mistake: Allowing thirsty patients to drink large volumes ad libitum causes more vomiting 1. Consider continuous nasogastric ORS infusion for intractable vomiting 1.

When Oral Rehydration Fails

Switch to IV therapy if:

• Progression to severe dehydration or shock 2
• Intractable vomiting despite small-volume technique 1
• Stool output >10 mL/kg/hour (though most still respond to adequate oral replacement) 1
• True glucose malabsorption (dramatic stool increase with ORS, immediate reduction with IV therapy—occurs in ~1% of cases) 1
• Intestinal ileus (wait until bowel sounds return) 1

Key Pitfalls to Avoid

• Do not withhold ORT for vomiting—use small, frequent volumes 1
• Do not use loperamide with bloody diarrhea or high fever—risk of toxic megacolon 4
• Do not routinely order stool cultures—reserve for severe illness, bloody stools, persistent fever, immunosuppression, or suspected outbreak 7, 8
• Do not fast patients—early refeeding speeds recovery in children and does not harm adults 1
• Do not use antidiarrheals in children <2 years—contraindicated due to serious adverse events 4