Macrobid Dosing for UTI
For uncomplicated UTI in adult women, the recommended dose is Macrobid (nitrofurantoin monohydrate/macrocrystals) 100 mg twice daily for 5-7 days. 1
Standard Dosing for Women
- The Infectious Diseases Society of America (IDSA) recommends 100 mg twice daily for 5-7 days as first-line therapy for uncomplicated cystitis in women 1, 2
- The 5-day regimen is equivalent to trimethoprim-sulfamethoxazole in clinical and microbiological cure rates (88-93% clinical cure, 81-92% bacterial cure) 1
- A 5-day course of nitrofurantoin is superior to single-dose fosfomycin, achieving 70% clinical resolution vs 58% with fosfomycin at 28 days 3
Dosing for Men
- For men with UTI, use 100 mg every 6 hours (four times daily) for 7-14 days 4
- The 14-day duration is recommended when prostatitis cannot be excluded 4
- Important caveat: Nitrofurantoin has substantially lower efficacy in males (25% failure rate) compared to females (10-16% failure rate), so consider alternative agents 4
Critical Contraindications
- Do not use if creatinine clearance is <60 mL/min due to inadequate urinary drug concentrations and increased risk of peripheral neuropathy 4
- Avoid if early pyelonephritis is suspected as nitrofurantoin does not achieve adequate tissue concentrations 1, 4
- Not recommended for perinephric abscess 1
Alternative Dosing Regimens
- For vancomycin-resistant Enterococci (VRE) UTIs: 100 mg four times daily 1
- Macrocrystals formulation: 50-100 mg four times daily for 5 days 1
Pediatric Dosing
- Children ≥12 years: 100 mg twice daily for 7 days 1
- Children <12 years: 5-7 mg/kg/day divided into 4 doses (maximum 100 mg/dose) for 7 days 1
Common Side Effects
- Nausea and headache are most common (adverse event rates 5.6-34%) 1
- Gastrointestinal effects including nausea (3%) and diarrhea (1%) 3
Key Clinical Pearls
- Nitrofurantoin is preferred as first-line therapy due to minimal resistance patterns and limited collateral damage to normal flora 1
- No routine post-treatment cultures needed if asymptomatic 1
- If symptoms persist or recur within 2 weeks, obtain urine culture with susceptibility testing and consider retreatment with a 7-day regimen using an alternative agent 1