Macrobid Dosing for Uncomplicated UTI
For uncomplicated urinary tract infections in women, prescribe Macrobid (nitrofurantoin monohydrate/macrocrystals) 100 mg orally twice daily for 5 days. 1, 2
Standard Adult Dosing
- The recommended dose is 100 mg twice daily for 5-7 days for uncomplicated cystitis in women 1, 2
- The 5-day regimen is the optimal duration endorsed by both the Infectious Diseases Society of America (IDSA) and European Society for Microbiology and Infectious Diseases (ESMID) 1, 2
- This 5-day course achieves clinical cure rates of 84-90% and bacterial cure rates of 92% at early follow-up 2, 3
Alternative Duration Options
- A 7-day course (100 mg twice daily) is acceptable and achieves clinical cure rates of 89-93% with bacterial cure rates of 86% 2
- Avoid 3-day regimens (100 mg four times daily) due to inferior efficacy, with only 88% clinical cure and 74% bacterial cure rates 2
Special Populations
- For vancomycin-resistant Enterococcus (VRE) UTIs: Use 100 mg four times daily 1, 2
- For children ≥12 years: Use the adult dose of 100 mg twice daily 1, 2
- For children <12 years: Use 5-7 mg/kg/day divided into 4 doses (maximum 100 mg/dose) for 7 days 1, 2
Critical Contraindications
- Do not use if creatinine clearance is <60 mL/min due to inadequate urinary drug concentrations and increased toxicity risk 2
- Avoid if early pyelonephritis is suspected as nitrofurantoin does not achieve adequate tissue concentrations for upper tract infections 1, 2
- Contraindicated in the last trimester of pregnancy 4
Expected Adverse Effects
- Nausea and headache are the most common side effects, occurring in 5.6-34% of patients 1, 2
- Serious adverse effects (pulmonary reactions, polyneuropathy) are rare and mainly occur with long-term use 4
When to Consider Alternatives
- If CrCl <60 mL/min: Switch to trimethoprim-sulfamethoxazole (if local resistance <20%) or fosfomycin 2
- If pyelonephritis is suspected: Use fluoroquinolones or other agents with adequate tissue penetration 1, 5
- Alternative first-line options include: Fosfomycin 3 g single dose (slightly lower efficacy at 90% vs 95% for nitrofurantoin) or trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days if local E. coli resistance is <20% 1, 2, 5