Macrobid (Nitrofurantoin) Dosing for Uncomplicated UTI
For uncomplicated urinary tract infections in women, the recommended dose is nitrofurantoin monohydrate/macrocrystals (Macrobid) 100 mg twice daily for 5-7 days. 1
Standard Dosing Regimen
The Infectious Diseases Society of America (IDSA) and European Society for Microbiology and Infectious Diseases (ESMID) recommend 100 mg twice daily for 5 days as the optimal first-line regimen for uncomplicated UTIs in women. 1
The 5-day regimen achieves clinical cure rates of 88-93% and bacterial cure rates of 81-92%. 1
A 7-day course is also acceptable and may be preferred in certain clinical scenarios, though 5 days is now considered optimal to minimize adverse effects while maintaining efficacy. 1, 2
Alternative Dosing for Specific Situations
For vancomycin-resistant enterococcal (VRE) UTIs specifically, increase the dose to 100 mg four times daily (every 6 hours). 1, 3
The macrocrystal formulation can alternatively be dosed at 50-100 mg four times daily for 5 days. 1
Critical Contraindications
Do not use nitrofurantoin if creatinine clearance is <60 mL/min due to inadequate urinary drug concentrations and increased toxicity risk. 3
Avoid nitrofurantoin if early pyelonephritis is suspected - it is only appropriate for uncomplicated lower UTI (cystitis). 1, 3
Not recommended for perinephric abscess. 4
Pediatric Dosing
For children ≥12 years: 100 mg/dose twice daily (same as adults). 4
For children <12 years: 5-7 mg/kg/day divided into 4 doses, with a maximum of 100 mg/dose. 4
Recommended duration is 7 days or at least 3 days after obtaining sterile urine in pediatric patients. 4
Common Pitfalls to Avoid
Do not extend treatment beyond 7 days unless symptoms persist - shorter courses minimize adverse effects (nausea and headache occur in 5.6-34% of patients). 1, 3
Routine post-treatment urine cultures are not indicated for asymptomatic patients. 1
If symptoms do not resolve by end of treatment or recur within 2 weeks, obtain urine culture with susceptibility testing and consider retreatment with a 7-day regimen using an alternative agent. 1
Comparative Efficacy
Nitrofurantoin demonstrates equivalent efficacy to trimethoprim-sulfamethoxazole (160/800 mg twice daily for 3 days) when comparing the 5-day nitrofurantoin regimen. 1
Similar clinical cure rates to ciprofloxacin when comparing 7-day regimens, but nitrofurantoin is preferred as first-line due to minimal resistance development and limited collateral damage to normal flora. 1, 2