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

Dosage for Macrobid (Nitrofurantoin) for Uncomplicated UTIs

The recommended dosage for Macrobid (nitrofurantoin monohydrate/macrocrystals) for uncomplicated urinary tract infections is 100 mg twice daily for 5 days. 1, 2

Standard Dosing Regimens

• Nitrofurantoin monohydrate/macrocrystals (Macrobid): 100 mg twice daily for 5 days is the first-line regimen recommended by the Infectious Diseases Society of America (IDSA) and the European Society for Microbiology and Infectious Diseases 1, 2
• Nitrofurantoin macrocrystals: 50-100 mg four times daily for 5 days is an alternative formulation 1
• Nitrofurantoin macrocrystals prolonged release: 100 mg twice daily for 5 days 1

Efficacy and Supporting Evidence

• Nitrofurantoin is recommended as a first-line agent due to minimal resistance and limited propensity for collateral damage 1, 2
• Clinical cure rates with nitrofurantoin range from 88-93% for uncomplicated UTIs in women 2, 3
• Bacterial cure rates range from 81-92% for uncomplicated UTIs 2, 3
• The 5-day regimen of nitrofurantoin has been shown to be equivalent to trimethoprim-sulfamethoxazole (160/800 mg twice daily for 3 days) in clinical and microbiological cure rates 2

Special Considerations

Renal Function

• Nitrofurantoin is contraindicated in patients with creatinine clearance <60 mL/min due to inadequate urinary drug concentrations and increased risk of toxicity 4
• For patients with reduced renal function, alternative agents such as trimethoprim-sulfamethoxazole or fosfomycin trometamol should be considered 4

Duration of Treatment

• While UK guidelines sometimes recommend 3-day courses, most international guidelines including the IDSA recommend 5-day courses 1, 2, 5
• The European Association of Urology specifically lists 5 days as the recommended duration 1
• There is limited direct evidence supporting 3-day courses of nitrofurantoin, unlike other antibiotics where shorter courses may be effective 5

Alternative Regimens for Specific Situations

• For VRE (Vancomycin-resistant Enterococci) uncomplicated UTIs: 100 mg four times daily is recommended 1, 2
• For men with UTIs: Limited observational studies support 7-14 days of therapy rather than the 5-day regimen used for women 6

Common Side Effects

• Nausea and headache are the most commonly reported side effects 2
• Adverse event rates range from 5.6-34% across studies 2

Monitoring

• 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 and antimicrobial susceptibility testing should be performed 1