Macrobid (Nitrofurantoin) Dosing Recommendations
For uncomplicated urinary tract infections, nitrofurantoin monohydrate/macrocrystals (Macrobid) should be dosed at 100 mg twice daily for 5 days. 1
Standard Dosing for Uncomplicated UTIs
- Nitrofurantoin monohydrate/macrocrystals (Macrobid): 100 mg twice daily for 5 days is the recommended first-line regimen for uncomplicated UTIs in women 1, 2
- This 5-day regimen has been shown to be equivalent to trimethoprim-sulfamethoxazole in clinical and microbiological cure rates 1
- Clinical cure rates with this regimen range from 88-93% for uncomplicated UTIs 1
- Bacterial cure rates range from 81-92% 1
Alternative Dosing for Specific Situations
- For VRE (Vancomycin-resistant Enterococci) uncomplicated UTIs: 100 mg PO four times daily 3
- Duration of therapy for uncomplicated UTIs: 3-7 days 3
- The 5-day regimen is supported by the Infectious Diseases Society of America and European Society for Microbiology and Infectious Diseases as optimal 1
Efficacy Considerations
- Nitrofurantoin has similar clinical cure rates to ciprofloxacin and trimethoprim-sulfamethoxazole when comparing treatment regimens 1
- In a randomized clinical trial, 5-day nitrofurantoin showed significantly better clinical resolution (70%) compared to single-dose fosfomycin (58%) 4
- Microbiological resolution was also superior with nitrofurantoin (74%) versus fosfomycin (63%) 4
Important Contraindications and Precautions
- Nitrofurantoin is contraindicated in patients with creatinine clearance <60 mL/min due to:
- Inadequate urinary drug concentrations
- Increased risk of toxicity, including peripheral neuropathy 2
- For patients with CrCl <60 mL/min, alternative agents such as trimethoprim-sulfamethoxazole or fosfomycin should be considered 2
Common Side Effects
- Most common adverse events include nausea and headache 1
- Overall adverse event rates range from 5.6-34% across studies 1
- Gastrointestinal side effects are most common, with nausea occurring in approximately 3% of patients 4
Clinical Pearls
- Nitrofurantoin is considered a first-line agent for uncomplicated UTIs due to minimal resistance and limited propensity for collateral damage 1
- Fluoroquinolones, while effective, should be reserved for more invasive infections to minimize resistance development 5
- Immediate antimicrobial therapy is recommended rather than delayed treatment or symptom management alone 5
- For long-term prophylaxis in elderly patients (though not first-line approach), a single evening dose of 100 mg has shown efficacy 6
This evidence-based approach to nitrofurantoin dosing provides clear guidance while recognizing important contraindications and monitoring requirements for optimal patient outcomes.