What is the recommended dose of Nitrofurantoin (antibiotic) for an uncomplicated urinary tract infection (UTI)?

Nitrofurantoin Dosing for Uncomplicated UTI

For uncomplicated urinary tract infections (UTIs) in women, nitrofurantoin monohydrate/macrocrystals should be dosed at 100 mg twice daily for 5-7 days. 1

Recommended Dosing Regimens

• Nitrofurantoin monohydrate/macrocrystals: 100 mg twice daily for 5-7 days 1
• Nitrofurantoin macrocrystals: 100 mg four times daily for 3 days (alternative regimen, but with lower bacterial cure rates) 1, 2

Efficacy Data

• Clinical cure rates with nitrofurantoin range from 88-93% 1
• Bacterial cure rates range from 81-92% 1
• The 5-day regimen of nitrofurantoin monohydrate/macrocrystals (100 mg twice daily) has been shown to be equivalent to trimethoprim-sulfamethoxazole (160/800 mg twice daily for 3 days) in clinical and microbiological cure rates 1

Comparative Efficacy

• Nitrofurantoin (100 mg twice daily for 5 days) demonstrated superior clinical resolution compared to single-dose fosfomycin (70% vs 58%) in a recent randomized clinical trial 3
• Microbiological resolution was also better with nitrofurantoin compared to fosfomycin (74% vs 63%) 3
• Nitrofurantoin has similar clinical cure rates to ciprofloxacin and trimethoprim-sulfamethoxazole when comparing 7-day regimens 1

Duration Considerations

• While some UK guidelines recommend 3-day courses of nitrofurantoin, there is limited direct evidence supporting this shorter duration 4
• The most robust evidence supports 5-7 day regimens for nitrofurantoin 1
• The Infectious Diseases Society of America (IDSA) and European Society for Microbiology and Infectious Diseases recommend 5-day regimens 1

Common Side Effects

• Nausea and headache are the most commonly reported side effects 1
• Adverse event rates range from 5.6-34% across studies 1
• Gastrointestinal side effects are generally mild and self-limiting 3

Special Considerations

• Nitrofurantoin is a first-line agent for uncomplicated UTIs due to minimal resistance and limited propensity for collateral damage 1
• The European Association of Urology also lists nitrofurantoin as a first-line treatment option for uncomplicated cystitis 1
• Nitrofurantoin should be avoided in patients with creatinine clearance <30 mL/min due to decreased efficacy and increased risk of toxicity 5

Algorithm for Treatment Selection

1. For uncomplicated UTI in non-pregnant women: Use nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 5 days as first-line therapy 1
2. If patient cannot tolerate twice-daily dosing: Consider alternative first-line agents like fosfomycin 3g single dose or trimethoprim-sulfamethoxazole (if local resistance <20%) 1
3. If patient has renal insufficiency (CrCl <30 mL/min): Avoid nitrofurantoin and select an alternative agent 5