Macrobid Dosing for Adults
For uncomplicated urinary tract infections in adults, the recommended dose of Macrobid (nitrofurantoin monohydrate/macrocrystals) is 100 mg orally 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 nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 5-7 days as first-line therapy for uncomplicated UTIs in women. 1
The 5-day regimen is now the preferred duration based on current guidelines, as it minimizes adverse effects while maintaining equivalent efficacy to longer courses. 1
Clinical cure rates with this regimen range from 88-93%, with bacterial cure rates of 81-92%. 1
Gender-Specific Considerations
For males with UTI, the dose is 100 mg orally every 6 hours (four times daily) for 7-14 days, with 14 days recommended when prostatitis cannot be excluded. 2
Nitrofurantoin has substantially lower efficacy in males compared to females, with a 25% failure rate in males versus 10-16% failure in females. 2
Alternative Dosing for Specific Organisms
For vancomycin-resistant Enterococcus (VRE) UTIs, use 100 mg orally four times daily. 1
The standard macrocrystal formulation can be dosed at 50-100 mg four times daily for 5 days as an alternative regimen. 1
Critical Contraindications
Do not use nitrofurantoin if creatinine clearance is <60 mL/min due to inadequate urinary drug concentrations and increased risk of toxicity, including peripheral neuropathy. 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 and in patients with any degree of renal impairment. 3
Common Pitfalls to Avoid
Do not extend treatment beyond 7 days unless symptoms persist, as longer courses increase the risk of serious adverse effects including pulmonary reactions and polyneuropathy without improving efficacy. 1
Ensure the patient has adequate hydration during treatment to prevent crystal formation. 4
Do not use for complicated UTIs, perinephric abscess, or upper urinary tract infections. 1
Monitoring and Follow-Up
Routine post-treatment urinalysis or urine cultures are not indicated for asymptomatic patients. 1
For patients whose symptoms do not resolve by the end of treatment or recur within 2 weeks, obtain urine culture with susceptibility testing and consider retreatment with a 7-day regimen using an alternative agent. 1