Fluid Rehydration in a 5-Year-Old with Food Poisoning
For a 5-year-old child with food poisoning, use oral rehydration solution (ORS) as first-line therapy, administering 50 mL/kg over 2-4 hours for mild dehydration or 100 mL/kg over 2-4 hours for moderate dehydration, then replace ongoing losses with 120-240 mL of ORS for each diarrheal stool or vomiting episode. 1
Initial Assessment
First, assess the degree of dehydration clinically:
- Mild dehydration (3-5% fluid deficit): Increased thirst, slightly dry mucous membranes 1
- Moderate dehydration (6-9% fluid deficit): Loss of skin turgor, skin tenting when pinched, dry mucous membranes 1
- Severe dehydration (≥10% fluid deficit): Severe lethargy or altered consciousness, prolonged skin tenting (>2 seconds), cool and poorly perfused extremities, decreased capillary refill 1
Weigh the child to calculate fluid requirements accurately. 1
Rehydration Phase
For Mild to Moderate Dehydration (Most Common Scenario)
Use oral rehydration solution exclusively—this is as effective as IV therapy and avoids complications like phlebitis. 1
Mild dehydration: Administer 50 mL/kg ORS over 2-4 hours 1
- For a 20 kg child, this equals approximately 1000 mL over 2-4 hours
Moderate dehydration: Administer 100 mL/kg ORS over 2-4 hours 1
- For a 20 kg child, this equals approximately 2000 mL over 2-4 hours
Administration technique matters: Start with small volumes (one teaspoon) using a teaspoon, syringe, or medicine dropper, then gradually increase as tolerated. 1 This is especially important if the child is vomiting—give 5 mL every 1-2 minutes rather than large volumes that will be rejected. 2
For Severe Dehydration (Medical Emergency)
Immediately initiate IV rehydration with isotonic crystalloid (normal saline or lactated Ringer's). 1
- Administer 20 mL/kg boluses until pulse, perfusion, and mental status normalize 1
- Once stabilized and the child is alert with no aspiration risk, transition to ORS for remaining deficit 1
Maintenance Phase and Ongoing Loss Replacement
After initial rehydration is complete (reassess at 2-4 hours), transition to maintenance therapy:
Replace ongoing losses with 120-240 mL ORS for each diarrheal stool or vomiting episode (for children >10 kg body weight, which includes your 5-year-old). 1 Continue this replacement as long as diarrhea or vomiting persists. 1
An alternative calculation: 10 mL/kg for each watery stool and 2 mL/kg for each vomiting episode. 3
Choice of ORS Product
Use only commercially available low-osmolarity ORS formulations such as Pedialyte, CeraLyte, or Enfalac Lytren. 1
For rehydration, solutions containing 75-90 mEq/L sodium are preferable, though solutions with 40-60 mEq/L sodium (like Pedialyte at 45 mEq/L) can be used effectively. 1, 4 When using lower sodium solutions for maintenance, ensure the child also receives other fluids or food to prevent sodium imbalance. 1
Critical Pitfalls to Avoid
- Never use apple juice, Gatorade, sports drinks, or soft drinks for rehydration—these contain inappropriate electrolyte content and excessive osmolality that can worsen diarrhea. 1, 2
- Do not give anti-diarrheal medications to children with acute diarrhea. 5
- Do not delay feeding—resume age-appropriate diet within 3-4 hours after rehydration is complete. 1, 5 Early feeding shortens the duration of diarrhea. 2
- Do not restrict fluids or use diluted formulas—these provide no benefit. 1
When to Escalate Care
Consider nasogastric tube administration at 15 mL/kg/hour if the child cannot tolerate oral intake but is not in shock. 5
Switch to IV therapy if:
- ORS therapy fails after appropriate trial 1
- Severe dehydration with shock is present 1
- Altered mental status exists 1
- Ileus is present 1
Monitoring
Reassess hydration status after 2-4 hours by checking skin turgor, mucous membranes, mental status, and perfusion. 1 If dehydration persists, reestimate the fluid deficit and restart rehydration therapy. 1