Dose is calculated using the trimethoprim component.
Max 100 mg/dose (trimethoprim) · Duration: Individualized · Reassess every 3–6 months · give at bedtime when possible
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Nitrofurantoin • p.o. • 1–2 mg/kg/dose • 1×/day
Max 100 mg/dose · Duration: Individualized · Reassess every 3–6 months · at bedtime · lower-tract prophylaxis only
• Acute episodes: treat per Acute Uncomplicated Cystitis (afebrile lower tract) or Acute Pyelonephritis / Febrile UTI (fever, flank pain, systemic signs) — culture-directed therapy.
• Nitrofurantoin: sulfa allergy, TMP/SMX intolerance, or breakthrough UTI on TMP/SMX; does not reach therapeutic renal parenchymal levels — not for acute pyelonephritis.
• Amoxicillin 10–20 mg/kg/day p.o. once daily: prophylaxis option in infants <2 months when prophylaxis is required (TMP/SMX and nitrofurantoin contraindicated).
• Antibiotic prophylaxis is not routine after a first uncomplicated UTI (AAP, NICE, CPS, ESPU/EAU); modest reduction in recurrence with increased resistance — shared decision-making.
• Prophylaxis may be considered: grade III–V VUR, VUR with recurrent UTI, BBD with recurrent UTI, non–toilet-trained child with VUR, or pending urology evaluation after abnormal imaging (AAP/CPS/CHOP).
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Clinical notes
• Recurrent UTI (AAP): ≥2 febrile UTIs, OR 1 febrile + ≥1 afebrile UTI, OR ≥3 afebrile UTIs; operational: ≥2 UTIs in 6 months OR ≥3 in 12 months.
• Urine culture: every symptomatic episode; before starting or changing prophylaxis; post-treatment culture in high-risk patients per local protocol.
• Renal/bladder ultrasound (RBUS): after first febrile UTI in young children; in recurrent UTI at any age; during acute illness if sepsis concern, poor response at 48 h, or suspected obstruction.
• VCUG: not routine after first febrile UTI (AAP); consider with abnormal RBUS, recurrent febrile UTI, high-grade VUR suspicion, atypical organism, or complex course (ESPU/EAU/CPS).
• Prevention: hydration, timed voiding, treat constipation and BBD, genital hygiene; discontinue prophylaxis when risk factors resolve — reassess every 3–6 months with urology/nephrology as indicated.
• AAP — Urinary Tract Infection Clinical Practice Guideline (2011)
• AAP Reaffirmation — Febrile UTI in infants and young children (2016)
• RIVUR Trial — Antimicrobial prophylaxis for vesicoureteral reflux (2014)
+ 5 more
• AAP Red Book — Urinary Tract Infections (2024)
• Canadian Paediatric Society — Urinary tract infections in children (2024)
