What is the appropriate treatment for an adult patient with nausea, vomiting and diarrhea?

Treatment of Nausea, Vomiting, and Diarrhea in Adults

Start oral rehydration therapy immediately with low-osmolarity oral rehydration solution (ORS), giving 200–400 mL after each loose stool, and once the patient is adequately hydrated, add loperamide 4 mg initially then 2 mg after each unformed stool (maximum 16 mg/24 hours) for watery diarrhea, plus ondansetron for significant vomiting to facilitate oral intake. 1

Initial Assessment and Risk Stratification

Hydration Status Evaluation:

• Check skin turgor, mental status, mucous membrane moisture, capillary refill, and vital signs to categorize dehydration as mild, moderate, or severe 1
• Tachycardia, hypotension, or altered mental status indicate severe dehydration requiring urgent IV fluids 1
• Document stool frequency (≥16 loose stools suggests moderate-to-severe disease), presence of blood, consistency, fever pattern, and associated vomiting or abdominal pain 1

Warning Signs Requiring Medical Evaluation:

• High fever (>38.5°C) with bloody stools (dysentery) 2
• Severe dehydration with shock or altered mental status 1
• Moderate-to-severe abdominal pain suggesting inflammatory process 2, 1
• Symptoms persisting >48 hours without improvement 1, 3
• Recent antibiotic exposure or immunocompromised status 3

Rehydration Strategy (First Priority)

Oral Rehydration Therapy:

• Use low-osmolarity ORS as first-line for mild-to-moderate dehydration; allow the patient to drink according to thirst 1
• Replace ongoing losses with approximately 200–400 mL of ORS after each loose stool 1
• ORS is superior to caffeinated beverages or soft drinks for rehydration 1

Intravenous Rehydration:

• Indicated for severe dehydration with shock, altered mental status, or inability to tolerate oral fluids 1, 3
• Continue IV fluids until pulse, perfusion, and mental status normalize, then transition to ORS 1

Pharmacologic Management

Antidiarrheal Therapy

Loperamide Dosing:

• Start with 4 mg loading dose, then 2 mg after each unformed stool, maximum 16 mg per 24 hours 2, 1, 3
• Critical: Only use after adequate hydration is achieved 2, 1
• Clinical improvement typically occurs within 48 hours; if no improvement, re-evaluate for infectious causes 1

Absolute Contraindications to Loperamide:

• Bloody or inflammatory diarrhea with fever 2, 1
• Moderate-to-severe abdominal pain suggesting toxic megacolon risk 2, 1
• Any signs of dehydration (must rehydrate first) 1
• Children <18 years of age 2
• Suspected inflammatory diarrhea or dysentery 2

Serious Safety Warning:

• Never exceed 16 mg/24 hours due to risk of QT prolongation, torsades de pointes, and fatal cardiac arrhythmias 1

Antiemetic Therapy

Ondansetron for Vomiting:

• Administer to adults with significant vomiting to improve ORS tolerance 2, 1, 3
• Ondansetron reduces immediate need for hospitalization or IV rehydration 2
• Important caveat: Ondansetron may increase stool volume/diarrhea as a side effect 2
• Ondansetron does not replace fluid and electrolyte therapy 2, 1
• Based on safety profile without sedation or akathisia, ondansetron is preferred over older agents like promethazine or prochlorperazine 4, 5

Alternative Antiemetics:

• Metoclopramide or prochlorperazine may be used but carry risk of akathisia requiring monitoring for 48 hours post-administration 4
• Promethazine causes more sedation and has potential for vascular damage with IV administration 4

Nutritional Management

Early Refeeding:

• Encourage resumption of normal, age-appropriate diet during or immediately after rehydration 2, 1, 3
• Early refeeding decreases intestinal permeability, reduces illness duration, and improves nutritional outcomes 2, 1
• No evidence supports routine restriction to BRAT diet or fasting for 24 hours 2, 1

Dietary Modifications:

• Eliminate lactose-containing products temporarily (reduces diarrhea duration by average 18 hours) 2
• Avoid high-osmolar dietary supplements, coffee, alcohol, and spicy foods 1, 3
• Small, frequent meals may be better tolerated than large meals 2

Diagnostic Evaluation

Obtain Stool Studies When:

• Bloody stools present 1, 3
• Persistent fever >38.5°C 1, 3
• Severe dehydration 1
• Symptoms lasting >48 hours without improvement 1, 3
• Immunocompromised status 3
• Recent antibiotic exposure (consider C. difficile) 6

Monitoring and Reassessment

Reassess If:

• No clinical improvement within 48 hours of initiating therapy 1, 3
• Diarrhea persists beyond one week 1
• New concerning symptoms develop (bloody stools, high fever, severe abdominal distension) 1
• Patient develops dizziness on standing, suggesting worsening dehydration 3

Antimicrobial Therapy Considerations

When to Consider Antibiotics:

• Quinolones (e.g., ciprofloxacin) are first-line for empirical treatment of dysentery or identified bacterial infectious diarrhea 2
• Can be safely combined with loperamide in mild febrile dysentery to hasten remission 2
• Short course (single dose to 2 days) typically induces remission within 1-3 days for traveler's diarrhea 2
• Do not use empirically for all acute diarrheal episodes due to increasing antimicrobial resistance 2

Critical Pitfalls to Avoid

• Do not delay ORT while awaiting diagnostic tests; start immediately 1, 3
• Do not give loperamide before adequate rehydration or in presence of fever with bloody diarrhea due to toxic megacolon risk 2, 1, 3
• Do not exceed 16 mg loperamide per day because of serious cardiac risks 1
• Do not unnecessarily restrict diet during or after rehydration 2, 1
• Do not use caffeinated beverages or soft drinks as primary rehydration fluids 1
• Do not confuse overflow diarrhea from fecal impaction (especially in elderly) with true diarrhea 1, 3
• Do not neglect hydration while focusing solely on symptom control 3

Escalation for Refractory Cases

If Standard Therapy Fails:

• Consider adding codeine 30 mg twice daily 1
• Consider octreotide 100-150 mcg subcutaneously three times daily for severe refractory diarrhea 1, 6
• Consider empiric fluoroquinolone antibiotics if infectious etiology suspected 1
• Hospitalization with IV fluids for complicated diarrhea with fever, severe pain, or persistent dehydration 3, 6