Recommended Dosage of Nitrofurantoin for Uncomplicated UTI
For uncomplicated urinary tract infections in women, nitrofurantoin should be administered as 100 mg twice daily for 5 days. 1
Dosing Options Based on Formulation
The dosage of nitrofurantoin varies based on the specific formulation:
- Nitrofurantoin monohydrate/macrocrystals: 100 mg twice daily for 5 days 1
- Nitrofurantoin macrocrystals: 50-100 mg four times daily for 5 days 1, 2
- Nitrofurantoin macrocrystals prolonged release: 100 mg twice daily for 5 days 1
Evidence Supporting This Recommendation
The 5-day regimen of nitrofurantoin is supported by high-quality evidence from both the Infectious Diseases Society of America (IDSA) and the European Association of Urology (EAU) guidelines. Clinical studies have demonstrated:
- Clinical cure rates of 88-93% and bacterial cure rates of 81-92% with nitrofurantoin regimens 1
- Comparable efficacy to trimethoprim-sulfamethoxazole when used for 5 days 1
- Superior efficacy compared to single-dose fosfomycin, with clinical resolution rates of 70% vs 58% respectively 3
Administration Considerations
- Nitrofurantoin should be given with food to improve drug absorption and tolerance 2
- For long-term suppressive therapy in adults, a reduced dosage of 50-100 mg at bedtime may be adequate 2
Important Clinical Considerations
First-line Status
Nitrofurantoin is considered a first-line treatment for uncomplicated UTI due to:
- Minimal resistance patterns
- Limited collateral damage to normal flora
- High efficacy rates comparable to other antibiotics 1
Treatment Duration
While some countries may recommend shorter 3-day courses 4, the strongest evidence supports a 5-day regimen for optimal clinical and microbiological cure 1, 3.
Contraindications and Cautions
- Contraindicated in patients under one month of age 2
- Use with caution in patients with renal impairment
- Not recommended for pyelonephritis or complicated UTIs
Follow-up
Routine post-treatment urinalysis or urine cultures are not indicated for asymptomatic patients 1. However, if symptoms persist or recur within 2 weeks after treatment completion, urine culture with antimicrobial susceptibility testing should be performed 1.
Alternative Treatments for Uncomplicated UTI
If nitrofurantoin cannot be used, alternative first-line options include:
For recurrent UTIs, when non-antimicrobial interventions have failed, continuous or post-coital antimicrobial prophylaxis may be considered 1.