Nitrofurantoin Dosing for Uncomplicated UTI
For adults with normal renal function and uncomplicated UTI, prescribe nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 5 days. 1
Standard Dosing Regimen
The recommended dose is nitrofurantoin monohydrate/macrocrystals 100 mg orally twice daily for 5-7 days, as endorsed by the Infectious Diseases Society of America (IDSA) and European Society for Microbiology and Infectious Diseases (ESMID) 1
Five days represents the optimal duration that balances efficacy (88-93% clinical cure rates) with minimizing antibiotic exposure and adverse effects 1
This 5-day regimen has equivalent efficacy to trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days 1
Alternative Dosing Formulations
Nitrofurantoin macrocrystals can be dosed at 50-100 mg four times daily for 5 days according to European Urology guidelines 1
For vancomycin-resistant enterococci (VRE) UTIs specifically, use 100 mg four times daily 1, 2
Critical Contraindications and Precautions
Avoid nitrofurantoin if early pyelonephritis is suspected, as it does not achieve adequate renal tissue concentrations 1
Contraindicated in patients with creatinine clearance <30 mL/min due to inadequate urinary drug concentrations and increased risk of peripheral neuropathy 1
The traditional cutoff of CrCl <60 mL/min may be overly restrictive—research suggests nitrofurantoin remains effective in patients with CrCl 30-60 mL/min 3, 4
Do not use in men with suspected prostatitis, as nitrofurantoin does not penetrate prostatic tissue adequately 1
Avoid in complicated UTIs (structural/functional abnormalities, obstruction, instrumentation, pregnancy) 1
Gender-Specific Considerations
For males with uncomplicated UTI, use 100 mg every 6 hours for 7-14 days (14 days when prostatitis cannot be excluded) 5
Males have substantially lower efficacy with nitrofurantoin (75% success rate versus 84-93% in females), so consider alternative agents like trimethoprim-sulfamethoxazole or fluoroquinolones for male patients 5
Common Adverse Effects
Nausea and headache are most common, with adverse event rates of 5.6-34% 1
Serious pulmonary and hepatic toxicity are extremely rare (0.001% and 0.0003% respectively) 1
Ensure adequate hydration during treatment to prevent crystal formation 1
Follow-Up Recommendations
Routine post-treatment urinalysis or urine cultures are not indicated for asymptomatic patients 1
For patients 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