First-Line Treatment for Dehydration
Reduced osmolarity oral rehydration solution (ORS) is the first-line treatment for mild to moderate dehydration in all age groups, regardless of the underlying cause. 1
Treatment Algorithm Based on Severity
Mild Dehydration (3-5% fluid deficit)
- Administer 50 mL/kg of ORS over 2-4 hours 2, 3
- Signs include increased thirst and slightly dry mucous membranes 2
- Start with small volumes (one teaspoon) using a syringe or medicine dropper, then gradually increase as tolerated 3
Moderate Dehydration (6-9% fluid deficit)
- Administer 100 mL/kg of ORS over 2-4 hours 2, 3
- Signs include loss of skin turgor and dry mucous membranes 2
- If oral intake fails, consider nasogastric administration at 15 mL/kg/hour 3
Severe Dehydration (≥10% fluid deficit)
- This is a medical emergency requiring immediate intravenous rehydration with isotonic fluids (lactated Ringer's or normal saline) 1, 2
- Administer 20 mL/kg IV boluses until pulse, perfusion, and mental status normalize 1, 3
- Signs include severe lethargy or altered consciousness and prolonged skin tenting 2
- Once stabilized, transition to ORS for remaining deficit replacement 1
Specific ORS Formulations
Use commercially available reduced osmolarity ORS (total osmolarity <250 mmol/L) containing 50-90 mEq/L of sodium 1, 2. The 2017 IDSA guidelines emphasize that the WHO-recommended hypotonic ORS replaced the older standard formulation (osmolarity 311 mmol/L) in 2002 due to better safety profile and reduced risk of hypernatremia 1.
Acceptable products include:
Do not use apple juice, Gatorade, or commercial soft drinks due to inappropriate electrolyte content and high osmolality 1, 3.
Replacing Ongoing Losses
After initial rehydration, replace ongoing losses with ORS until diarrhea and vomiting resolve 1:
- Children <10 kg: 60-120 mL per diarrheal stool or vomiting episode 3
- Children >10 kg: 120-240 mL per diarrheal stool or vomiting episode 3
- Alternative calculation: 10 mL/kg per watery stool and 2 mL/kg per vomiting episode 3
Nutritional Management
Resume age-appropriate normal diet during or immediately after rehydration is complete 1. The evidence shows early feeding (within 12 hours) improves nutritional outcomes without increasing complications 1.
- Breastfed infants must continue nursing throughout the illness 1, 3
- Bottle-fed infants should receive full-strength formula (lactose-containing formulas are tolerated in most cases; diluted formula offers no benefit) 1, 2
- Avoid prolonged fasting or "resting the bowel" 2
When ORS Fails
Switch to intravenous rehydration if:
- Severe dehydration, shock, or altered mental status present 1
- Paralytic ileus develops 1
- Patient cannot tolerate oral/nasogastric intake 1
- ORS therapy fails (occurs in approximately 4% of cases) 1
- Ketonemia prevents oral tolerance (may need initial IV hydration) 1
Critical Monitoring Parameters
Reassess hydration status after 2-4 hours by evaluating 2, 3:
- Skin turgor and mucous membranes
- Urine output
- Vital signs (pulse, perfusion, mental status)
- Capillary refill time (though affected by fever, temperature, and age) 2
The evidence from a meta-analysis of 17 RCTs 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 1. However, IV therapy caused more phlebitis, supporting ORS as the safer first-line approach 1.
Important Contraindications
Do not use antimotility drugs (e.g., loperamide) in children <18 years of age 1, 3. These medications are not substitutes for proper fluid and electrolyte therapy 1.