Nitrofurantoin Dosing for Uncomplicated UTI
For uncomplicated UTIs in women, use nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 5 days as first-line therapy. 1
Standard Dosing for Women with Uncomplicated Cystitis
The recommended regimen is 100 mg twice daily for 5-7 days, with 5 days being the optimal duration endorsed by both the Infectious Diseases Society of America (IDSA) and European Society for Microbiology and Infectious Diseases (ESMID). 1
This 5-day regimen achieves clinical cure rates of 88-93% and bacterial cure rates of 81-92% in women with uncomplicated UTIs. 1
The 5-day course is equivalent in efficacy to trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days, making it an excellent first-line choice. 1
Important Caveat on Duration
While UK guidelines have promoted 3-day courses of nitrofurantoin, there is little direct evidence supporting this shorter duration, and international consensus favors 5-7 days. 2 The 5-day regimen provides better assurance of adequate treatment while maintaining the benefits of shorter antibiotic exposure. 1
Dosing for Men with UTI
For men with uncomplicated UTI, use nitrofurantoin 100 mg every 6 hours (four times daily) for 7-14 days. 3
Treat for 14 days when prostatitis cannot be excluded, as men are at higher risk for prostatic involvement. 3
Be aware that nitrofurantoin has substantially lower efficacy in males compared to females, with a 25% failure rate in males versus 10-16% failure in females. 3 Consider alternative agents like trimethoprim-sulfamethoxazole 160/800 mg twice daily for 14 days or fluoroquinolones for 5-7 days based on susceptibility testing. 3
Special Pathogen Considerations
Vancomycin-Resistant Enterococci (VRE) or Enterococcus faecalis
For uncomplicated UTIs caused by VRE, use nitrofurantoin 100 mg four times daily (every 6 hours). 1, 4
Continue treatment for 7-10 days until clinical resolution for enterococcal UTIs. 4
Alternative options include fosfomycin 3 g as a single dose or high-dose ampicillin/amoxicillin. 4
Critical Contraindications and Precautions
Do not use nitrofurantoin if creatinine clearance is <60 mL/min due to inadequate urinary drug concentrations and increased risk of peripheral neuropathy and other toxicities. 3, 4
Avoid nitrofurantoin if early pyelonephritis is suspected, as it does not achieve adequate tissue concentrations for upper tract infections. 1, 3
Do not use for perinephric abscess. 1
Common Side Effects
Nausea and headache are the most frequently reported adverse effects, with overall adverse event rates ranging from 5.6-34%. 1
Serious reactions like rash may occur, requiring discontinuation in some patients. 5
Follow-Up Recommendations
Routine post-treatment urinalysis or urine cultures are not indicated for asymptomatic patients. 1
For women 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 an alternative agent. 1
Monitor for clinical response within 48-72 hours of initiating treatment in men. 3