From the Guidelines
Nitrofurantoin is recommended for uncomplicated urinary tract infections at a dosage of 100 mg taken orally every 12 hours for 5 days, as supported by the most recent guidelines 1.
Dosage and Administration
- The recommended dosage is 100 mg taken orally every 12 hours for 5 days, or as macrocrystals (Macrobid) 100 mg twice daily with food.
- For severe infections, treatment may be extended to 7-10 days.
- An alternative regimen is 50-100 mg four times daily for 7 days.
- For UTI prophylaxis, 50-100 mg at bedtime may be used.
Important Considerations
- Nitrofurantoin should be taken with food to enhance absorption and reduce gastrointestinal side effects.
- It's most effective for lower UTIs caused by susceptible organisms like E. coli.
- Nitrofurantoin is not recommended for upper UTIs, pyelonephritis, or in patients with creatinine clearance below 60 mL/min due to reduced urinary concentration.
- The medication works by damaging bacterial DNA and is particularly effective in the acidic environment of urine.
- Common side effects include nausea, vomiting, and diarrhea.
- Nitrofurantoin is contraindicated in patients with G6PD deficiency, during late pregnancy (38-42 weeks), and in infants under one month.
- Patients should complete the full course of treatment even if symptoms improve before finishing the medication.
Evidence-Based Recommendations
- The American College of Physicians recommends short-course antibiotics with either nitrofurantoin for 5 days, trimethoprim–sulfamethoxazole (TMP–SMZ) for 3 days, or fosfomycin as a single dose for women with uncomplicated bacterial cystitis 1.
- The Infectious Diseases Society of America (IDSA) and the European Society for Microbiology and Infectious Diseases (ESCMID) also recommend nitrofurantoin as a first-line treatment option for uncomplicated UTIs 1.
From the Research
Nitrofurantoin Dosage and Guidelines for UTI
- The typical dosage of nitrofurantoin for uncomplicated urinary tract infections (UTIs) is 100 mg twice daily for 5-7 days 2.
- However, some guidelines recommend a 3-day course of nitrofurantoin at 100 mg twice daily as first-line treatment for uncomplicated UTI 3.
- The effectiveness of nitrofurantoin in treating UTIs has been demonstrated in several studies, with clinical resolution rates ranging from 58% to 70% 2.
- Nitrofurantoin is considered a key oral antibiotic option for treating acute uncomplicated cystitis (AUC) due to multi-drug resistant (MDR) Gram-negative bacilli (GNB) 4.
- The use of nitrofurantoin is not recommended if the creatinine clearance (CrCl) is less than 60 ml/min, but some studies suggest that it can be effective in patients with CrCl between 30-60 ml/min 4, 5.
Renal Insufficiency and Nitrofurantoin Use
- Patients with renal insufficiency (CrCl < 60 ml/min) may have decreased nitrofurantoin efficacy, but the drug can still be effective in treating UTIs in this population 4, 5.
- A study found that nitrofurantoin eradicated the uropathogen in 69% of patients with renal insufficiency (CrCl < 60 ml/min), with only two failures due to renal insufficiency (CrCl < 30 ml/min) 4.
- Another study found that the presence of mild or moderate reductions in estimated glomerular filtration rate did not justify avoidance of nitrofurantoin 5.
Comparison with Other Antibiotics
- Nitrofurantoin has been compared to other antibiotics, such as fosfomycin, in the treatment of UTIs, with nitrofurantoin showing a significantly greater likelihood of clinical and microbiologic resolution at 28 days after therapy completion 2.
- A review of international guidelines found that the evidence base for nitrofurantoin has been interpreted in different ways, with varying recommendations for dosage and duration of treatment 3.