What is the appropriate dose of Motrin (ibuprofen) 100 mg/5 mL for a child weighing 101 lb (≈46 kg)?

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Last updated: February 12, 2026View editorial policy

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Ibuprofen Dosing for 101-Pound Child

For a child weighing 101 pounds (approximately 46 kg), administer 15 mL of Motrin 100 mg/5 mL suspension (300 mg) every 6-8 hours as needed, not exceeding four doses in 24 hours.

Weight-Based Dosing Calculation

  • Standard pediatric ibuprofen dosing is 10 mg/kg per dose, given every 6-8 hours 1, 2.

  • For a 46 kg child: 10 mg/kg × 46 kg = 460 mg per dose would be the weight-based calculation 1.

  • However, children weighing more than 40 kg (88 pounds) should receive adult dosing rather than continuing weight-based pediatric calculations 3, 1.

  • The standard adult dose of ibuprofen is 200-400 mg every 6-8 hours, with a maximum of 1200 mg per day for over-the-counter use 1.

Practical Dosing with Available Formulation

  • With Motrin 100 mg/5 mL suspension, 15 mL delivers 300 mg, which falls appropriately within the adult dosing range 1.

  • This can be administered every 6-8 hours (maximum 3-4 times in 24 hours), providing a total daily dose of 900-1200 mg 3, 1.

  • The dose of 300 mg (15 mL) is conservative and safe, avoiding the upper limit while providing effective antipyretic and analgesic effects 2, 4.

Clinical Considerations

  • Maximum fever reduction occurs 3-4 hours after administration of ibuprofen 2.

  • The effective dose range demonstrated in clinical trials is 7.5-10 mg/kg, with the relationship between dose and response being linear over the 5-10 mg/kg range 2.

  • Ibuprofen has been shown to be equally or more effective than acetaminophen as an antipyretic and analgesic, with a longer duration of action 2, 5.

  • Ensure adequate hydration when administering ibuprofen, as this is particularly important for safety in all pediatric patients 4.

Safety Parameters

  • Do not exceed four doses in 24 hours to avoid inadvertently exceeding maximum recommended daily dosing 5.

  • Parents should carefully record all dose times to prevent accidental overdosing, especially if alternating with acetaminophen 5.

  • Ibuprofen is generally well-tolerated in children and is considered safer in overdose than acetaminophen 2.

References

Guideline

Pediatric Acetaminophen and Ibuprofen Dosing Guidelines

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

Research

A general overview of the use of ibuprofen in paediatrics.

International journal of clinical practice. Supplement, 2003

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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