What is the best course of treatment for a patient with a 2-week history of headaches, diarrhea, vomiting, nausea, stomach pain, and cramping, along with a mild runny nose?

Management of Acute Gastroenteritis with 2-Week Duration

This patient requires oral rehydration therapy as first-line treatment, early resumption of normal diet, and consideration of ondansetron for persistent vomiting to facilitate oral intake, while avoiding antimotility agents and unnecessary antibiotics. 1, 2

Initial Assessment and Hydration Status

The 2-week duration of symptoms suggests acute gastroenteritis, most likely viral in etiology given the constellation of GI symptoms with mild upper respiratory symptoms and no recent travel. 3 The priority is assessing hydration status by evaluating:

• Mental status, pulse quality, and perfusion 2
• Skin turgor, mucous membrane moisture, and capillary refill 1
• Urine output and presence of orthostatic symptoms 2

Rehydration Strategy

Oral rehydration solution (ORS) with reduced osmolarity is the cornerstone of treatment for mild to moderate dehydration. 1, 2

• Administer 50-100 mL/kg of ORS over 3-4 hours for initial rehydration 1
• If vomiting is prominent, give small frequent volumes (5-10 mL) every 1-2 minutes, gradually increasing as tolerated 1
• Nasogastric ORS administration may be considered if oral intake fails but mental status is normal 1, 2
• IV fluids are reserved only for severe dehydration, shock, altered mental status, or ORS failure 2

Dietary Management

Resume normal age-appropriate diet immediately after rehydration is complete—do not withhold food. 1, 2

• Early refeeding decreases intestinal permeability, reduces illness duration, and improves nutritional outcomes 3
• The BRAT diet has limited supporting evidence and is not specifically recommended 3
• Avoid prolonged fasting, which can worsen outcomes 3

Antiemetic Therapy for Persistent Vomiting

Ondansetron can be administered to facilitate oral rehydration in patients with significant vomiting. 3, 1

• Dosing: 0.15-0.2 mg/kg orally (maximum 4 mg per dose) 4
• Ondansetron reduces vomiting and decreases need for hospitalization or IV rehydration 3
• Important caveat: Ondansetron may increase stool volume/diarrhea as a side effect 3, 5
• Monitor for rare but serious adverse effects including QT prolongation and serotonin syndrome, particularly if patient is on other serotonergic medications 5

What NOT to Do: Critical Pitfalls

Antimotility agents (loperamide) are contraindicated in this scenario. 3, 1, 2

• Never give loperamide to patients <18 years of age with acute diarrhea 3, 1
• Even in adults, avoid loperamide when fever is present or inflammatory diarrhea is suspected, as it risks toxic megacolon 3, 2

Empiric antibiotics are NOT indicated. 2

• This patient has no recent travel, no bloody diarrhea, and likely viral etiology 2
• Antibiotics should only be considered for: immunocompromised patients, infants <3 months with suspected bacterial etiology, fever with bloody diarrhea suggesting shigellosis, or recent international travel with high fever ≥38.5°C 2
• Antibiotics are specifically contraindicated if STEC (Shiga toxin-producing E. coli) is suspected, as they increase risk of hemolytic uremic syndrome 2

When to Seek Further Evaluation

Red flags requiring immediate medical attention include: 2

• Development of bloody diarrhea (suggests bacterial pathogen requiring stool culture and possible antimicrobials) 1, 2
• Signs of severe dehydration despite ORS attempts 2
• Altered mental status or toxic appearance 2
• Inability to tolerate any oral fluids 1
• Significant worsening of symptoms or high fever development 1

Symptomatic Adjuncts

For headache and cramping pain, acetaminophen or ibuprofen can provide symptomatic relief while maintaining hydration. 6 The mild runny nose requires no specific treatment and likely represents concurrent viral upper respiratory symptoms. 6

The key principle is that rehydration—not pharmacologic intervention—is the primary treatment, with early feeding resumption to optimize recovery. 1, 2