Macrobid Dosing for Uncomplicated UTI
For uncomplicated urinary tract infections, the recommended dose of Macrobid (nitrofurantoin monohydrate/macrocrystals) is 100 mg twice daily for 5-7 days. 1
Standard Dosing Regimen
The Infectious Diseases Society of America (IDSA) and European Society for Microbiology and Infectious Diseases (ESMID) recommend 100 mg twice daily for 5 days as the optimal first-line regimen for uncomplicated UTIs in women. 1
The 5-day regimen achieves clinical cure rates of 88-93% and bacterial cure rates of 81-92%, which is equivalent to trimethoprim-sulfamethoxazole for 3 days. 1
The European Association of Urology also endorses 100 mg twice daily for 5 days as first-line therapy for uncomplicated cystitis. 1
Alternative Dosing for Specific Situations
For vancomycin-resistant enterococcal (VRE) UTIs specifically, increase the dose to 100 mg four times daily (every 6 hours) for 7-10 days. 2
The older 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 monohydrate/macrocrystal formulation. 1
Duration Considerations
Five days is the preferred duration for standard uncomplicated UTIs, balancing efficacy with minimizing adverse effects. 1
Seven-day regimens may be considered for patients with diabetes (who should otherwise be treated similarly to non-diabetic women), men with UTIs, or when symptoms persist beyond initial treatment. 1, 3
Do not extend treatment beyond 7 days unless symptoms persist, as shorter courses minimize adverse effects while maintaining efficacy. 1
Critical Contraindications
Nitrofurantoin is absolutely contraindicated if creatinine clearance is <60 mL/min due to inadequate urinary drug concentrations and increased toxicity risk. 2
Avoid nitrofurantoin if early pyelonephritis is suspected, as it does not achieve adequate tissue concentrations outside the urinary tract. 1
Contraindicated in the last trimester of pregnancy (last 3 months) due to risk of hemolytic anemia in the newborn. 4
Common Pitfalls to Avoid
Do not use single-dose therapy—this has been shown to be statistically less effective than 3-7 day regimens. 5
Do not routinely order post-treatment urinalysis or urine cultures in asymptomatic patients, as this is not indicated. 1
If 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 a different agent. 1
Expected Adverse Effects
Nausea and headache are the most common side effects, with overall adverse event rates ranging from 5.6-34%. 1
Serious side effects like pulmonary reactions and polyneuropathy mainly occur with long-term use, not short-course therapy. 4