What is the dosing volume of amoxicillin (400 mg per 5 mL) for a child?

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Last updated: July 3, 2025View editorial policy

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From the Guidelines

The dosing volume of amoxicillin for a child is determined by the child's weight and the condition being treated, with typical dosing ranging from 45-90 mg/kg/day divided into two or three doses. For most common pediatric infections, the recommended dose of amoxicillin is 45-90 mg/kg/day, as stated in the guidelines by the Pediatric Infectious Diseases Society and the Infectious Diseases Society of America 1.

  • The dosing can be calculated based on the child's weight, with a general guideline of 45-90 mg/kg/day.
  • For example, for a 20 kg child requiring 50 mg/kg/day, the daily dose would be 1000 mg, which is equivalent to 12.5 mL of the 400 mg/5 mL suspension, divided into two doses of 6.25 mL each.
  • It is essential to measure liquid medication using a calibrated device, such as an oral syringe or medicine cup, for accuracy.
  • The suspension should be shaken well before measuring each dose and refrigerated between uses.
  • Amoxicillin can be given with or without food, though taking with food may help reduce stomach upset.
  • Treatment duration typically ranges from 5-10 days, depending on the infection type, and the full course should be completed even if symptoms improve before finishing the medication to prevent antibiotic resistance and ensure complete eradication of the infection, as recommended by the guidelines 1.

From the FDA Drug Label

Each 5 mL of reconstituted suspension contains 125 mg or 250 mg of amoxicillin as the trihydrate.

The dosing volume of amoxicillin for a child, given the concentration of 400 mg per 5 mL, cannot be directly determined from the provided FDA drug label, as it only mentions concentrations of 125 mg/5 mL and 250 mg/5 mL.

From the Research

Dosing Volume of Amoxicillin

To determine the dosing volume of amoxicillin for a child, we need to consider the concentration of the medication, which is 400 mg per 5 mL.

  • The dosing volume will depend on the prescribed dose, which is typically based on the child's weight.
  • According to 2, prescribing on an age basis may be acceptable for drugs such as amoxicillin, but it is imperative to prescribe on a mg/kg basis for accurate dosing.
  • However, none of the provided studies directly address the calculation of dosing volume based on the concentration of 400 mg per 5 mL.
  • The studies primarily focus on the efficacy, safety, and usage of amoxicillin and amoxicillin-clavulanic acid combinations in various infections, as well as the importance of accurate prescribing practices 3, 4, 5, 6.

Calculation of Dosing Volume

  • To calculate the dosing volume, we would typically need to know the prescribed dose in milligrams and the concentration of the medication.
  • Assuming a prescribed dose, we can calculate the dosing volume using the formula: dosing volume (mL) = prescribed dose (mg) / concentration (mg/mL).
  • For example, if the prescribed dose is 200 mg, the dosing volume would be 200 mg / (400 mg/5 mL) = 2.5 mL.
  • However, without a specific prescribed dose, we cannot determine the exact dosing volume.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

How good are doctors at estimating children's weight?

Journal of accident & emergency medicine, 1997

Research

Oral amoxicillin and amoxicillin-clavulanic acid: properties, indications and usage.

Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases, 2020

Research

Alternative Antibiotic Selections During the 2022 Amoxicillin Shortage in the United States.

Journal of the Pediatric Infectious Diseases Society, 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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