What is the recommended dosage of Macrobid (nitrofurantoin monohydrate) for treating uncomplicated urinary tract infections?

Macrobid Dosing for Uncomplicated UTI

For uncomplicated urinary tract infections in adults, the recommended dose of Macrobid (nitrofurantoin monohydrate/macrocrystals) is 100 mg twice daily for 5 days. 1

Standard Dosing Regimen

• The Infectious Diseases Society of America (IDSA) and European Society for Microbiology and Infectious Diseases (ESMID) consistently recommend 100 mg twice daily for 5 days as the optimal first-line regimen for uncomplicated UTIs in women. 1

• The European Association of Urology also endorses this same 5-day regimen as first-line treatment for uncomplicated cystitis. 1

• This dosing achieves clinical cure rates of 88-93% and bacterial cure rates of 81-92% for uncomplicated UTIs. 1, 2

Alternative Dosing for Specific Situations

• For VRE (vancomycin-resistant Enterococci) uncomplicated UTIs specifically, increase the dose to 100 mg four times daily. 1

• The macrocrystal formulation (not Macrobid) can be dosed at 50-100 mg four times daily for 5 days, though this is less convenient than the twice-daily Macrobid formulation. 1

Duration Considerations

• The 5-day duration is strongly preferred over shorter 3-day courses, as international guidelines consistently support 5 days for optimal efficacy. 1

• While some UK guidance suggests 3-day courses, there is little direct evidence supporting this shorter duration, and it may compromise treatment success. 3

• The 5-day nitrofurantoin regimen has been shown equivalent to 3-day trimethoprim-sulfamethoxazole courses in both clinical and microbiological cure rates. 1

• Treatment should not extend beyond 7 days unless symptoms persist, as shorter courses minimize adverse effects while maintaining efficacy. 1

Critical Contraindications

• Nitrofurantoin is absolutely contraindicated in patients with creatinine clearance <60 mL/min due to inadequate urinary drug concentrations and increased risk of peripheral neuropathy and other toxicities. 2

• Avoid nitrofurantoin if early pyelonephritis is suspected, as it does not achieve adequate tissue concentrations for upper tract infections. 1

• Nitrofurantoin is contraindicated in the last three months of pregnancy. 4

Common Pitfalls to Avoid

• Do not use the older macrocrystal formulation dosed four times daily when Macrobid (monohydrate/macrocrystals) is available, as twice-daily dosing improves adherence without compromising efficacy. 1

• Do not routinely order post-treatment urinalysis or urine cultures in asymptomatic patients, as this is not indicated. 1

• For patients whose symptoms do not resolve by end of treatment or recur within 2 weeks, obtain urine culture with susceptibility testing and consider retreatment with a 7-day regimen using another agent. 1

Tolerability Profile

• Nausea and headache are the most commonly reported side effects, with adverse event rates ranging from 5.6-34% across studies. 1

• Serious side effects like pulmonary reactions and polyneuropathy mainly occur with long-term use, not with short 5-day courses. 4