Nitrofurantoin (Macrobid) Dosing for Urinary Tract Infections
For uncomplicated urinary tract infections in adults, the recommended dose of nitrofurantoin monohydrate/macrocrystals (Macrobid) is 100 mg twice daily for 5-7 days. 1
Standard Dosing Regimens
- The Infectious Diseases Society of America recommends nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 5-7 days as a first-line treatment for uncomplicated UTIs in women 1
- Clinical cure rates with this regimen range from 88-93% for uncomplicated UTIs 1
- Bacterial cure rates range from 81-92% when using this dosing regimen 1
- The 5-day regimen has been shown to be equivalent to trimethoprim-sulfamethoxazole (160/800 mg twice daily for 3 days) in clinical and microbiological outcomes 1
Alternative Dosing Regimens
- For treatment of UTIs caused by vancomycin-resistant enterococci (VRE), a higher dose of 100 mg every 6 hours (four times daily) is recommended 2
- Some formulations of nitrofurantoin macrocrystals can be used at 50-100 mg four times daily for 5 days according to European guidelines 1
- Single-dose therapy with nitrofurantoin is not recommended, unlike fosfomycin which can be given as a single dose 1, 3
Special Populations and Considerations
- Nitrofurantoin is contraindicated in patients with creatinine clearance <60 mL/min due to:
- Inadequate urinary drug concentrations
- Increased risk of toxicity, including peripheral neuropathy 4
- For patients with renal impairment, alternative agents such as trimethoprim-sulfamethoxazole or fosfomycin should be considered 4
- Immediate antimicrobial therapy is recommended rather than delayed treatment or symptom management with NSAIDs alone 3
Common Side Effects
- The most commonly reported side effects are nausea and headache 1
- Adverse event rates range from 5.6-34% across clinical studies 1
- For better tolerability, the daily dose should be administered in two divided doses rather than once daily 5
Efficacy and Comparative Data
- Nitrofurantoin has been shown to be significantly more effective than placebo in achieving both bacteriological cure and symptomatic relief within three days 6
- It has similar clinical cure rates to ciprofloxacin and trimethoprim-sulfamethoxazole when comparing 7-day regimens 1
- Fluoroquinolones, while effective, should be reserved for more invasive infections due to concerns about resistance 3
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 the end of treatment or recur within 2 weeks, a urine culture with susceptibility testing should be performed 1
- If symptoms persist or recur, retreatment with a 7-day regimen using another agent should be considered 1