Pediatric Amoxicillin Dosage Calculator

The Pediatric Amoxicillin Dosage Calculator computes weight-based amoxicillin doses for common pediatric infections, supporting accurate prescribing of the most widely used antibiotic in pediatric medicine. Amoxicillin, a broad-spectrum aminopenicillin, is the first-line antibiotic for numerous pediatric conditions including acute otitis media, streptococcal pharyngitis, sinusitis, urinary tract infections, and various respiratory infections.

Dosing of amoxicillin varies significantly by indication, reflecting differences in the pharmacokinetics needed to achieve adequate tissue levels at different infection sites and against different pathogens. Standard dosing for susceptible infections is 25 mg/kg/dose given twice daily (total 50 mg/kg/day). High-dose therapy for acute otitis media and sinusitis uses 40-45 mg/kg/dose twice daily (total 80-90 mg/kg/day) to achieve adequate middle ear and sinus fluid levels against increasingly resistant Streptococcus pneumoniae.

The shift to high-dose amoxicillin for acute otitis media was driven by increasing pneumococcal resistance, particularly intermediate-resistant strains with MIC values of 1-2 mcg/mL. Standard-dose amoxicillin achieves middle ear fluid concentrations of approximately 3-5 mcg/mL, which may be insufficient for these strains. High-dose therapy achieves levels of 8-12 mcg/mL, exceeding the MIC for most intermediate-resistant pneumococci.

For streptococcal pharyngitis (strep throat), amoxicillin at 25 mg/kg/dose twice daily for 10 days is the standard regimen, equivalent to the traditional penicillin V protocol but with better taste and fewer daily doses, improving compliance. Complete 10-day therapy is essential for preventing rheumatic fever, regardless of symptom resolution.

Amoxicillin is available in multiple suspension concentrations: 125 mg/5 mL, 200 mg/5 mL, 250 mg/5 mL, and 400 mg/5 mL. Higher concentrations are preferred for older or larger children to reduce the volume per dose, improving palatability and compliance. The calculator converts the mg dose to the appropriate volume based on the selected concentration.

Duration of therapy varies by indication: 10 days for acute otitis media and streptococcal pharyngitis, 10-14 days for sinusitis, 7-10 days for urinary tract infections, and 7-10 days for most other infections. Shorter courses may be appropriate for uncomplicated infections in selected patients, as emerging evidence supports shorter antibiotic courses for many pediatric conditions.

Important prescribing considerations include: allergy history (true penicillin allergy occurs in approximately 1-2% of children, and many reported allergies are not true IgE-mediated reactions), concurrent illness, recent antibiotic use (which may indicate resistant organisms), and local resistance patterns. Amoxicillin should be reconstituted according to manufacturer instructions and stored in the refrigerator after mixing.