Macrobid Dosing for Uncomplicated UTI
For uncomplicated urinary tract infections in women, prescribe nitrofurantoin monohydrate/macrocrystals (Macrobid) 100 mg twice daily for 5 days. 1
Standard Dosing for Women
The IDSA and European Society for Microbiology and Infectious Diseases recommend 100 mg twice daily for 5 days as the optimal first-line regimen for uncomplicated cystitis in women. 1
This 5-day course achieves clinical cure rates of 88-93% and bacterial cure rates of 81-92%, which is equivalent to trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days. 1
The European Association of Urology also endorses nitrofurantoin as first-line therapy at 100 mg twice daily for 5 days. 1
Alternative Dosing Formulations
Nitrofurantoin macrocrystals can be dosed at 50-100 mg four times daily for 5 days if the twice-daily formulation is unavailable. 1
For VRE (vancomycin-resistant Enterococci) UTIs specifically, increase to 100 mg four times daily. 1
Dosing for Men
For males with uncomplicated UTI, prescribe nitrofurantoin 100 mg every 6 hours (four times daily) for 7-14 days, with 14 days recommended when prostatitis cannot be excluded. 2
Critical Caveat for Males
Nitrofurantoin has substantially lower efficacy in males, with a 25% failure rate compared to 10-16% in females. 2
Consider alternative agents (trimethoprim-sulfamethoxazole 160/800 mg twice daily for 14 days or fluoroquinolones for 5-7 days) as first-line options in males due to this higher failure rate. 2
Absolute Contraindications
Do not prescribe nitrofurantoin if creatinine clearance is <60 mL/min due to inadequate urinary drug concentrations and increased risk of peripheral neuropathy. 2
Avoid if early pyelonephritis is suspected, as nitrofurantoin does not achieve adequate tissue concentrations for upper tract infections. 1
Contraindicated in the last trimester of pregnancy (last 3 months). 3
Pediatric Dosing
For children ≥12 years: 100 mg twice daily for 7 days. 1
For children <12 years: 5-7 mg/kg/day divided into 4 doses (maximum 100 mg/dose) for 7 days or at least 3 days after obtaining sterile urine. 1
Common Pitfalls to Avoid
Do not extend treatment beyond 7 days in women unless symptoms persist, as shorter courses minimize adverse effects (nausea, headache) while maintaining efficacy. 1
Do not order routine post-treatment urinalysis or urine cultures for asymptomatic patients. 1
For women whose 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 another agent. 1
When to Choose Alternatives
If local E. coli resistance to trimethoprim-sulfamethoxazole is <20%, consider TMP-SMX 160/800 mg twice daily for 3 days as an alternative first-line option. 1
Fosfomycin trometamol 3 g single dose is an alternative with slightly lower efficacy than nitrofurantoin. 1
Reserve fluoroquinolones for more invasive infections due to resistance concerns and collateral damage to normal flora. 1