What is the treatment for a patient with diarrhea, considering potential underlying conditions such as diabetes or heart disease?

Treatment of Diarrhea

Oral rehydration solution (ORS) is the first-line treatment for any patient with diarrhea and mild to moderate dehydration—it is superior to IV fluids, safer, less costly, and equally effective. 1, 2

Immediate Rehydration Strategy

Assess hydration status first by evaluating thirst, orthostasis, decreased urination, dry mucous membranes, and altered mental status. 1

Mild to Moderate Dehydration (Most Patients)

• Administer reduced osmolarity ORS (osmolarity <250 mmol/L) containing approximately Na 90 mM, K 20 mM, Cl 80 mM, HCO₃ 30 mM, and glucose 111 mM. 1, 3
• Dosing for mild dehydration (3-5% deficit): Give 50 mL/kg ORS over 2-4 hours. 2, 3
• Dosing for moderate dehydration (6-9% deficit): Give 100 mL/kg ORS over 2-4 hours. 3
• For adults: Provide as much ORS as they want to drink. 2
• Critical technique: Administer ORS slowly using a spoon or syringe (5 mL every 1-2 minutes) rather than allowing rapid drinking from a cup, which worsens vomiting and leads to ORS failure. 3
• If vomiting prevents oral intake, consider nasogastric administration of ORS. 1

Severe Dehydration (≥10% Deficit)

Reserve IV fluids only for: 1, 2, 3

• Severe dehydration with signs of shock
• Altered mental status
• Hemodynamic instability
• Failure of ORS therapy after adequate trial
• Intestinal ileus

IV fluid protocol: 3

• Administer 20 mL/kg boluses of lactated Ringer's solution or normal saline
• Continue until pulse, perfusion, and mental status normalize
• Then transition to ORS for remaining deficit replacement

Nutritional Management

Resume age-appropriate diet immediately during or after rehydration—never withhold food or "rest the bowel." 1, 2

• Continue breastfeeding throughout the diarrheal episode without interruption. 1, 3
• Early realimentation prevents malnutrition and may reduce stool output. 1
• In children 6 months to 5 years in zinc-deficient regions or with malnutrition, add oral zinc supplementation. 1

Ongoing Fluid Replacement

Replace ongoing stool losses with approximately 10 mL/kg of ORS for each watery stool until diarrhea resolves. 2, 3

When to Consider Antimicrobials (Rarely)

Empiric antimicrobial therapy is NOT recommended for most patients with acute watery diarrhea. 1, 2

Consider antimicrobials ONLY in these specific circumstances: 1, 2

• Immunocompromised patients with severe illness
• Ill-appearing young infants
• Bloody diarrhea with presumptive shigellosis
• Recent international travelers with fever ≥38.5°C or signs of sepsis
• Clinical features of sepsis with suspected enteric fever

Never give antimicrobials in STEC O157 or Shiga toxin 2-producing E. coli infections—they increase risk of hemolytic uremic syndrome. 1

Adjunctive Therapies

Loperamide (Use With Extreme Caution)

Loperamide may be given ONLY to immunocompetent adults with acute watery diarrhea after adequate hydration. 2, 4

Absolute contraindications to loperamide: 1, 4

• All children <18 years of age (risk of respiratory depression and cardiac adverse reactions)
• Any patient with bloody diarrhea
• Fever present
• Suspected inflammatory diarrhea (risk of toxic megacolon)
• Patients taking QT-prolonging drugs (antiarrhythmics, antipsychotics, certain antibiotics)
• Patients with cardiac arrhythmias, long QT syndrome, or electrolyte abnormalities

Loperamide carries serious cardiac risks including QT prolongation, Torsades de Pointes, ventricular arrhythmias, cardiac arrest, and death, particularly with doses exceeding recommendations. 4

Antiemetics

• Ondansetron may be given to children >4 years and adolescents to facilitate oral rehydration when vomiting is present. 1

Probiotics

• Probiotics may be offered to reduce symptom severity and duration in immunocompetent patients, though evidence is moderate. 1

Special Populations

Patients with Heart Disease or Diabetes

• Monitor for overhydration in patients with chronic heart or kidney failure during ORS administration. 3
• Elderly patients have the highest risk of complications and require aggressive ORS therapy for grade 2 or higher diarrhea. 3
• Dehydration and electrolyte abnormalities can precipitate cardiac arrhythmias—avoid loperamide entirely in patients with underlying cardiac conditions. 4

Critical Pitfalls to Avoid

• Do not order routine stool cultures in uncomplicated acute watery diarrhea—most cases are viral and self-limited. 2
• Do not start IV fluids prematurely when oral rehydration is feasible. 2
• Do not use soft drinks, apple juice, Gatorade, or sports drinks for rehydration due to inappropriate osmolality—use proper ORS formulations. 2, 3
• Do not prescribe empiric antibiotics for undifferentiated watery diarrhea—this promotes resistance without benefit. 2
• Do not withhold ORS simply because of high stool output (>10 mL/kg/hour)—most patients still respond with adequate replacement. 3
• Reassess frequently during fluid administration to ensure dehydration is not worsening. 3