Dose is calculated using the amoxicillin component.
Max 875 mg/dose (amoxicillin) · Duration: 3–5 days · Amoxicillin component dosing; adjust per culture and local resistance
• Amoxicillin/clavulanate: beta-lactamase–producing organisms suspected, recent UTI treatment failure, or local E. coli resistance to cephalexin.
• Cefixime: alternative oral third-generation cephalosporin when first-line agents are unsuitable; good empiric choice in many regions per CPS (check local antibiogram).
• Cefalexin 25 mg/kg/dose p.o. 2×/day for 3 days is used in several cystitis protocols when adherence allows — consider per local guideline.
• Nitrofurantoin macrocrystal/monohydrate 100 mg p.o. 2×/day for 5 days may be used in adolescents when weight-based immediate-release dosing is impractical.
Enter weight on Kids to calculate doses
Clinical notes
• Uncomplicated cystitis = lower tract infection without fever, flank pain, or systemic toxicity; do not use nitrofurantoin for pyelonephritis.
• Obtain urine culture before antibiotics when feasible; tailor therapy to susceptibilities and local resistance patterns.
• Nitrofurantoin: contraindicated in infants <1 month; avoid if estimated CrCl <60 mL/min (immediate-release) or <30 mL/min (Macrobid).
• Reassess at 48–72 h if symptoms persist; consider complicated UTI, inadequate adherence, or resistant organism.
• Shorter oral courses (3–5 days) are appropriate for uncomplicated cystitis when clinical response is prompt (CPS, NICE principles).
• AAP — Urinary Tract Infection Clinical Practice Guideline (2011)
• AAP Red Book — Urinary Tract Infections (2024)
• Canadian Paediatric Society — Urinary tract infections in children (2024)
