What is the recommended ibuprofen dosage for a 3‑year‑old child weighing 31 lb?

Recommended Ibuprofen Dosage for a 3-Year-Old Weighing 31 Pounds

For a 3-year-old child weighing 31 pounds (14.1 kg), the recommended ibuprofen dose is 5-10 mg/kg per dose, given every 6-8 hours as needed, which translates to approximately 70-140 mg per dose, with a maximum daily dose not exceeding 40 mg/kg or 400 mg per dose.

Weight-Based Dosing Calculation

• At 31 pounds (14.1 kg), using the standard pediatric dosing of 5-10 mg/kg per dose:

  • Lower end: 14.1 kg × 5 mg/kg = 70.5 mg per dose
  • Upper end: 14.1 kg × 10 mg/kg = 141 mg per dose 1

• Practical dosing using available formulations:

  • Children's ibuprofen suspension typically comes as 100 mg/5 mL (20 mg/mL)
  • For this weight, administer 75-100 mg (approximately 3.75-5 mL) per dose for mild to moderate pain/fever
  • For more severe symptoms, 100-140 mg (5-7 mL) per dose may be used 1, 2

Dosing Frequency and Maximum Daily Limits

• Administer every 6-8 hours as needed, not to exceed 4 doses in 24 hours 1

• Maximum daily dose should not exceed 40 mg/kg/day (approximately 560 mg/day for this child) 1, 2

• Individual doses should not exceed 400 mg, though this is well above what this child would receive at appropriate weight-based dosing 3

Clinical Context and Efficacy

• Ibuprofen is more effective than acetaminophen (paracetamol) as an antipyretic in pediatric patients 1

• The onset of action is rapid, with peak analgesic effect occurring within 1-2 hours after oral administration 4

• Duration of action for a single dose is approximately 6-8 hours, which guides the dosing interval 3

Administration Recommendations

• Administer with food or milk to minimize gastrointestinal side effects, though this may slightly delay absorption 4, 5

• Use a calibrated oral dosing syringe or measuring device to ensure accurate dosing—never use household spoons 1

• Shake suspension formulations well before each use to ensure uniform drug distribution 5

Safety Profile at Pediatric Doses

• At appropriate pediatric doses (5-10 mg/kg), ibuprofen has an excellent safety profile with minimal risk of serious adverse events 1, 2

• The short plasma half-life of elimination (approximately 2 hours) and lack of toxic metabolites contribute to the favorable safety profile in children 1, 4

• Gastrointestinal, renal, and hepatic adverse effects are rare at standard pediatric doses and short-term use (less than 10 days) 1, 2

Critical Pitfalls to Avoid

• Do not exceed 40 mg/kg/day total daily dose—overdosing is more likely when caregivers use multiple products containing ibuprofen simultaneously 1

• Do not use ibuprofen in children with dehydration or significant volume depletion until hydration status is corrected, as this increases risk of renal complications 1

• Avoid chronic use without medical supervision—the safety data supporting ibuprofen's favorable profile applies primarily to short-term use (less than 10 days) 2

• Do not use adult formulations or adult fixed doses for pediatric patients—always calculate based on actual body weight in kilograms 1

When to Seek Medical Attention

• If fever persists beyond 3 days or pain beyond 5 days despite appropriate ibuprofen dosing 2

• If the child develops signs of dehydration, persistent vomiting, or refuses oral fluids 1

• If any signs of allergic reaction, unusual bleeding, or severe abdominal pain occur 1, 2