Macrobid Dosing and Duration for Uncomplicated UTI
For uncomplicated urinary tract infections in adults, prescribe Macrobid (nitrofurantoin monohydrate/macrocrystals) 100 mg twice daily for 5 days. 1
Standard Dosing Regimen
The Infectious Diseases Society of America (IDSA), American College of Physicians, and European Association of Urology all recommend nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 5 days as first-line therapy for uncomplicated UTIs in women. 1, 2
This 5-day regimen achieves clinical cure rates of 88-93% and bacterial cure rates of 81-92%. 1, 2
The 5-day course is equivalent in efficacy to trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days, with both achieving approximately 90% clinical cure rates. 1
Alternative Dosing Options
For vancomycin-resistant Enterococcus (VRE) UTIs specifically, increase the dose to 100 mg four times daily. 1
Nitrofurantoin macrocrystals (not the monohydrate/macrocrystal formulation) can be dosed at 50-100 mg four times daily for 5 days, though this is less convenient than twice-daily Macrobid. 1
Critical Contraindications
Do not use nitrofurantoin if early pyelonephritis is suspected—it does not achieve adequate tissue concentrations for upper tract infections. 1
Nitrofurantoin is contraindicated when creatinine clearance is <60 mL/min due to inadequate urinary drug concentrations and increased risk of peripheral neuropathy and other toxicities. 2
However, one retrospective study found nitrofurantoin remained effective in patients with CrCl 30-60 mL/min (69% eradication rate), though this contradicts guideline recommendations. 3 Follow the guideline contraindication at CrCl <60 mL/min to minimize toxicity risk. 2
Duration Considerations: Why Not 3 Days?
While some UK guidelines suggest 3-day courses, the consensus from IDSA, European Society for Microbiology and Infectious Diseases (ESMID), and European Association of Urology is 5 days as the optimal duration. 1
A 2023 review found little direct evidence supporting 3-day courses of nitrofurantoin, noting that duration recommendations for other antibiotics cannot be extrapolated to nitrofurantoin. 4
Do not extend treatment beyond 7 days unless symptoms persist, as shorter courses minimize adverse effects while maintaining efficacy. 1
Common Pitfalls to Avoid
Nausea and headache are the most common side effects, occurring in 5.6-34% of patients. 1
Do not prescribe for perinephric abscess or complicated UTIs—nitrofurantoin is only for uncomplicated lower tract infections. 1
For patients with CrCl <60 mL/min, switch to alternative agents such as trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days (if local resistance <20%) or fosfomycin trometamol 3 g single dose. 2