From the Guidelines
Nitrofurantoin is an effective first-line antibiotic for uncomplicated urinary tract infections (cystitis) in women, with a recommended dosage of 100 mg twice daily for 5 days, as supported by the most recent guidelines from the American College of Physicians 1.
Key Points
- The recommended dosage of nitrofurantoin for uncomplicated cystitis in women is 100 mg twice daily for 5 days, or 50-100 mg four times daily for 5 days 1.
- For men with uncomplicated cystitis, a 7-day course is typically recommended.
- Nitrofurantoin should be taken with food to improve absorption and reduce gastrointestinal side effects.
- It is contraindicated in patients with creatinine clearance less than 30 mL/min, during pregnancy at term (38-42 weeks), during labor and delivery, and in infants under one month of age due to risk of hemolytic anemia.
- Common side effects include nausea, headache, and urine discoloration.
- Patients should complete the full course of antibiotics even if symptoms improve before completion.
Rationale
The American College of Physicians recommends short-course antibiotics with either nitrofurantoin for 5 days, trimethoprim-sulfamethoxazole (TMP-SMX) for 3 days, or fosfomycin as a single dose for women with uncomplicated bacterial cystitis 1. Nitrofurantoin works by damaging bacterial DNA and inhibiting protein synthesis, and it achieves high concentrations in urine while maintaining low serum levels, making it ideal for treating lower urinary tract infections while minimizing systemic effects. It has low resistance rates compared to other antibiotics, making it particularly valuable for uncomplicated cystitis.
Evidence
Studies have shown that nitrofurantoin has similar clinical cure rates to other antibiotics, such as ciprofloxacin and TMP-SMX, and is effective in treating uncomplicated cystitis in women 1. The IDSA/European Society of Clinical Microbiology and Infectious Diseases (ESCMID) guideline recommends treatment durations depending on the type of antibiotic, including 5 days of nitrofurantoin, 3 days of TMP-SMX, or a single dose of fosfomycin 1.
From the Research
Efficacy of Nitrofurantoin for Cystitis
- Nitrofurantoin has been shown to be effective in treating acute uncomplicated cystitis, with clinical cure rates comparable to other antibiotics such as trimethoprim-sulfamethoxazole and quinolones 2, 3.
- A study found that a 5-day course of nitrofurantoin was equivalent to a 3-day course of trimethoprim-sulfamethoxazole in terms of clinical and microbiological cure rates 3.
- Nitrofurantoin has been recommended as a first-line antibiotic for the empiric treatment of uncomplicated cystitis in otherwise healthy women by several treatment guidelines, including those from the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases 2, 4.
Antimicrobial Activity of Nitrofurantoin
- Nitrofurantoin has been found to retain antimicrobial activity against multidrug-resistant urinary Escherichia coli, with resistance rates of only 2.1% to 24.1% in isolates resistant to three, four, or five antimicrobial agents 5.
- Nitrofurantoin has been shown to be effective against common uropathogens, including Escherichia coli, Staphylococcus saprophyticus, and Enterococcus species 2, 6.
- The use of nitrofurantoin has been increasing due to its low frequency of utilization and high susceptibility in common UTI pathogens, making it a potential first-line therapy for uncomplicated lower urinary tract infection (UTI) 6.
Safety and Side Effects of Nitrofurantoin
- Nitrofurantoin has been associated with several adverse drug effects, including pulmonary reactions and polyneuropathy, which mainly occur with long-term use 2.
- Short-term nitrofurantoin therapy has been shown to be well-tolerated, with a good safety profile 3.
- However, nitrofurantoin is contraindicated in the last three months of pregnancy and in patients with renal impairment of any degree 2.