What is the recommended dose of metronidazole (metro) syrup based on a child's weight?

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Metronidazole Syrup Dosing for Children Based on Weight

The recommended dose of metronidazole syrup for children with non-severe infections is 7.5 mg/kg/dose given three or four times daily, with a maximum dose of 500 mg per dose. 1

Dosing Guidelines by Indication

For Clostridium difficile Infection (CDI)

  • Initial episode, non-severe CDI: 7.5 mg/kg/dose three or four times daily for 10 days 1
  • Maximum dose: 500 mg per dose
  • Total daily dose: 22.5-30 mg/kg/day divided into 3-4 doses

For Other Common Pediatric Indications

  • Anaerobic infections: 7.5 mg/kg/dose given 3-4 times daily 1, 2
  • SIBO (Small Intestinal Bacterial Overgrowth): Similar dosing as for non-severe infections 3
  • Parasitic infections: Dosing may vary based on the specific parasite

Dosing Considerations

Age and Weight Adjustments

  • The dose should always be calculated based on the child's weight
  • For very young infants, consult with a pediatric infectious disease specialist
  • For children ≥35 kg, adult dosing may be appropriate

Duration of Treatment

  • CDI: 10 days 1
  • Anaerobic infections: 10-14 days (may be longer for severe infections) 2
  • SIBO: 10-14 days 3

Special Considerations

Malnourished Children

  • Malnourished children may require dose reduction due to altered drug metabolism
  • Consider reducing the dose to approximately 12 mg/kg/day in severely malnourished children 4
  • More frequent monitoring for adverse effects is recommended

Alternative Dosing Approaches

  • Some centers have explored once-daily dosing (30 mg/kg/day) for certain indications like appendicitis, but this is not standard practice for most infections 5

Important Precautions

  • Avoid prolonged or repeated courses due to risk of cumulative and potentially irreversible neurotoxicity 1, 3
  • Advise caregivers that children should avoid products containing alcohol during treatment
  • Monitor for common side effects: nausea, metallic taste, darkened urine
  • For severe infections, consider IV formulation initially (30 mg/kg/day divided into 3 doses) 2

Administration Tips

  • Metronidazole syrup can be given with or without food
  • If gastrointestinal upset occurs, administer with food
  • Shake the bottle well before measuring the dose
  • Use a calibrated measuring device for accurate dosing

Remember that metronidazole is a valuable antibiotic for anaerobic infections, but should be used judiciously to minimize the risk of adverse effects and antimicrobial resistance.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Treatment of anaerobic infections in children with metronidazole.

Developmental pharmacology and therapeutics, 1983

Guideline

SIBO Treatment Guidelines

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Research

A new dosing regimen for metronidazole in malnourished children.

Scandinavian journal of infectious diseases, 1993

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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