What is the appropriate management for a young adult with prolonged vomiting and diarrhea?

Management of Prolonged Vomiting and Diarrhea in a 25-Year-Old

For this 25-year-old with prolonged vomiting and diarrhea, initiate oral rehydration solution (ORS) as first-line therapy if mild-to-moderately dehydrated, assess for severe dehydration requiring IV fluids, resume normal diet immediately upon rehydration, and investigate for non-infectious causes given the prolonged duration. 1

Initial Assessment and Hydration Status

Assess hydration severity immediately to determine treatment pathway:

• Mild-to-moderate dehydration (3-9% fluid deficit): Patient has normal mental status, adequate perfusion, and stable vital signs 1
• Severe dehydration (≥10% fluid deficit): Presents with altered mental status, shock, poor perfusion, or hemodynamic instability requiring immediate IV intervention 1

The physical examination is the most reliable method for determining hydration status in adults 2

Rehydration Strategy

For Mild-to-Moderate Dehydration

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

• Give 50-100 mL/kg over 2-4 hours depending on dehydration severity 1
• Start with small volumes and gradually increase as tolerated 1
• Replace ongoing stool losses with 10 mL/kg of ORS for each watery stool 1
• Replace vomiting losses with 2 mL/kg of ORS for each emesis episode 1

Consider ondansetron to facilitate oral rehydration tolerance if vomiting is prominent, though this patient at age 25 is beyond the pediatric guideline age range of >4 years 1, 3

For Severe Dehydration

Initiate immediate IV rehydration with isotonic fluids:

• Administer lactated Ringer's or normal saline boluses (20 mL/kg) until pulse, perfusion, and mental status normalize 1
• Continue IV fluids until the patient is hemodynamically stable with normal mental status 1
• Transition to ORS for remaining fluid deficit once patient can tolerate oral intake 1

Nutritional Management

Resume age-appropriate normal diet immediately upon rehydration or during the rehydration process:

• Do not withhold food during diarrheal illness 1
• Recommended foods include starches, cereals, yogurt, fruits, and vegetables 1
• Avoid foods high in simple sugars and fats 1

Antimicrobial Considerations

Empiric antimicrobial therapy is NOT recommended for most adults with acute watery diarrhea without recent international travel 1, 4

However, given the prolonged duration ("long time"), this case warrants further investigation:

• Empiric antimicrobials should be avoided in persistent watery diarrhea lasting ≥14 days 1
• Consider diagnostic workup for non-infectious causes including inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) 4
• Obtain stool studies if fever ≥38.5°C, bloody diarrhea, severe abdominal pain, or signs of sepsis are present 4

If antimicrobials are indicated based on identified pathogen, modify or discontinue once organism is identified 1, 4

Adjunctive Therapies

Loperamide may be considered as this patient is an immunocompetent adult:

• Can be given for acute watery diarrhea in adults 1
• Avoid if fever, bloody stools, or inflammatory diarrhea suspected due to risk of toxic megacolon 1
• Use only after adequate hydration is achieved 1

Probiotics may be offered to reduce symptom severity and duration in immunocompetent adults 1, 4

Critical Pitfalls to Avoid

• Do not use antimotility agents if inflammatory diarrhea or fever present - risk of toxic megacolon 1, 4
• Do not give routine antimicrobials for watery diarrhea - increases resistance and provides no benefit 1, 4
• Do not withhold food during illness - early refeeding improves outcomes 1, 4
• Do not neglect rehydration while focusing on other therapies - fluid replacement is the cornerstone of management 1, 4

Special Considerations for Prolonged Duration

The "long time" duration raises concern for:

• Non-infectious etiologies requiring different management approaches 4
• Possible need for colonoscopy or imaging if symptoms persist beyond 14 days 4
• Evaluation for malabsorption syndromes, celiac disease, or chronic infections 4

Ensure proper hand hygiene after toilet use, before food preparation, and before eating to prevent transmission 1, 4