Nitrofurantoin Dosing for UTI in Children
Nitrofurantoin at 5-7 mg/kg/day divided into 4 doses (maximum 100 mg/dose) is the recommended dosing for uncomplicated lower urinary tract infections in children, but it should NOT be used for febrile UTIs, pyelonephritis, or any upper tract infection due to insufficient tissue and serum concentrations. 1
Critical Limitation: Not for Febrile or Upper Tract Infections
- Nitrofurantoin is contraindicated in febrile infants and children with UTIs because it does not achieve therapeutic concentrations in the bloodstream or renal parenchyma necessary to treat pyelonephritis or urosepsis 1
- The American Academy of Pediatrics explicitly states that agents excreted in urine but lacking adequate serum concentrations, such as nitrofurantoin, should not be used for febrile UTIs 1
Appropriate Use: Uncomplicated Lower UTI Only
Standard Treatment Dosing
- 5-7 mg/kg/day orally divided into 4 doses (maximum 100 mg per dose) 1
- Treatment duration: 7 days minimum, or at least 3 days after obtaining sterile urine 1
- Not approved for children under 12 years by Taiwan FDA, though widely used off-label 1
Alternative Role: Prophylaxis for Recurrent UTI
- 1.2-2.4 mg/kg/day as a single daily dose for prophylaxis in girls with recurrent lower UTI 2
- Prophylaxis reduces recurrence from 4.2 episodes/patient/year to 0.2 episodes/patient/year 2
- However, in children with neurogenic bladder on intermittent catheterization, nitrofurantoin prophylaxis does not effectively eradicate bacteriuria and promotes resistant organisms (Klebsiella, Pseudomonas) while reducing E. coli infections 3
Duration Considerations
- 3-day courses are used in some settings for uncomplicated lower UTI in girls, with similar efficacy to 10-day courses (relapse rates 7.7% vs 8.7%, reinfection rates 23% vs 30%) 4
- However, UK guidelines promoting 3-day courses lack robust supporting evidence, and clinical response varies widely 5
- 7-day minimum duration is safer based on guideline recommendations for febrile UTI extrapolated to lower tract infections 1
Preferred Alternatives for Febrile/Upper UTI in Children
When treating febrile UTI or suspected pyelonephritis, use instead:
- Oral options: Cephalosporins (cefixime 8 mg/kg/day, cefpodoxime 10 mg/kg/day divided twice daily), amoxicillin-clavulanate 20-40 mg/kg/day in 3 doses, or trimethoprim-sulfamethoxazole 6-12 mg/kg trimethoprim component per day in 2 doses 1
- Parenteral options for toxic-appearing children: Ceftriaxone 75 mg/kg every 24 hours, cefotaxime 150 mg/kg/day divided every 6-8 hours, or gentamicin 7.5 mg/kg/day divided every 8 hours 1
Key Clinical Pitfall
The most common error is using nitrofurantoin for any child with fever and UTI symptoms. Always assess for fever, flank pain, or systemic symptoms—if present, nitrofurantoin is inappropriate regardless of age. 1 Reserve nitrofurantoin exclusively for afebrile children with dysuria, frequency, and urgency suggesting isolated bladder infection.