What is the most appropriate initial treatment for a 2-year-old female with a 2-day history of vomiting and diarrhea, presenting with low-grade fever, irritability, and mild dehydration?

Oral Rehydration Therapy with ORS

The most appropriate initial treatment is oral rehydration solution (ORS) containing 50-90 mEq/L sodium, administered at 50 mL/kg over 2-4 hours, as this child demonstrates mild dehydration. 1, 2

Clinical Assessment of Dehydration Severity

This child's presentation indicates mild dehydration (3-5% fluid deficit) based on the following clinical findings:

• Presence of tears when crying suggests adequate hydration status (absence of tears is more concerning) 3
• Capillary refill of 2-3 seconds is at the upper limit of normal but not severely prolonged 3
• Irritability without altered mental status indicates mild rather than moderate-to-severe dehydration 1, 3
• Low-grade fever with vomiting and diarrhea for 2 days without signs of shock or severe lethargy 2

The absence of severe lethargy, prolonged skin tenting, or altered consciousness rules out moderate (6-9% deficit) or severe (≥10% deficit) dehydration. 3

Specific Rehydration Protocol

Administer 50 mL/kg of ORS over 2-4 hours using small, frequent volumes:

• Start with one teaspoon (5 mL) every 1-2 minutes using a teaspoon, syringe, or medicine dropper 1, 4
• Gradually increase volume as tolerated by the child 1
• For a typical 2-year-old weighing 12 kg, this equals approximately 600 mL total over 2-4 hours 1
• Replace ongoing losses with 10 mL/kg for each watery stool and 2 mL/kg for each vomiting episode 1, 2

Critical pitfall to avoid: Do not allow ad libitum drinking in vomiting patients, as this worsens vomiting—small, frequent volumes are essential. 4

Reassessment After Initial Rehydration

After 2-4 hours, reassess hydration status:

• If rehydrated (improved skin turgor, moist mucous membranes, normal mental status, adequate urine output), transition to maintenance therapy 1, 2
• If still dehydrated, reestimate the fluid deficit and restart rehydration therapy 1
• Success rate exceeds 90% with proper oral rehydration technique 5

Nutritional Management

Resume age-appropriate feeding immediately after rehydration is complete:

• Continue normal diet without "resting the bowel" 2, 3
• Offer foods every 3-4 hours as tolerated, including starches, cereals, yogurt, fruits, and vegetables 1, 4
• Avoid foods high in simple sugars and fats 1
• If breastfed, continue nursing on demand throughout the illness 1, 2

When to Escalate to IV Therapy

Switch to intravenous rehydration only if:

• Severe dehydration develops (≥10% fluid deficit, shock, altered mental status) 1, 2
• Persistent vomiting prevents oral intake despite small-volume administration 3
• Paralytic ileus develops 3
• ORS therapy fails after adequate trial 3

For severe dehydration requiring IV therapy, administer 20 mL/kg boluses of Ringer's lactate or normal saline until pulse, perfusion, and mental status normalize. 1, 2

Evidence Supporting Oral Rehydration

A meta-analysis of 17 randomized controlled trials involving 1,811 pediatric patients demonstrated no clinically important differences between ORS and IV therapy in rehydration success, weight gain, electrolyte abnormalities, or diarrhea duration, with ORS being the safer first-line approach. 3 The failure rate for ORT is only 4%, meaning one in 25 children will require IV therapy. 6