Macrobid (Nitrofurantoin) Prescription for Uncomplicated UTI
For uncomplicated urinary tract infections in women, prescribe nitrofurantoin monohydrate/macrocrystals (Macrobid) 100 mg twice daily for 5 days. 1
Standard Dosing Algorithm
For Women with Uncomplicated Cystitis
- Primary regimen: Nitrofurantoin monohydrate/macrocrystals 100 mg orally twice daily for 5 days 1
- This achieves clinical cure rates of 88-93% and bacterial cure rates of 81-92% 1
- The 5-day regimen is equivalent to trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days in efficacy 1
For Men with Uncomplicated UTI
- Extended duration required: Nitrofurantoin monohydrate/macrocrystals 100 mg orally twice daily for 7 days (not 5 days) 2
- Men require longer treatment based on observational data showing better outcomes with extended therapy 2
Alternative Dosing for Specific Pathogens
- For vancomycin-resistant enterococci (VRE) UTIs: Nitrofurantoin 100 mg orally every 6 hours (four times daily) for 7-10 days 3
- Alternative macrocrystal formulation: 50-100 mg four times daily for 5 days 1
Critical Contraindications and Precautions
Renal Function Requirements
- Absolute contraindication: Creatinine clearance <60 mL/min per FDA labeling 2
- Always check renal function before prescribing—this is the most dangerous error to avoid 2
- The American Geriatrics Society specifically warns against use when CrCl <60 mL/min due to inadequate urinary drug concentrations and increased risk of peripheral neuropathy 2
- Expert consensus recommends avoiding nitrofurantoin in older adults with CrCl <30 mL/min 2
Note: While emerging research 4 suggests nitrofurantoin may be effective in patients with CrCl 30-60 mL/min (69% cure rate), current FDA and guideline recommendations maintain the <60 mL/min contraindication, and you should follow these official guidelines in clinical practice 2
Clinical Scenario Contraindications
- Do not use if pyelonephritis is suspected—nitrofurantoin does not achieve adequate tissue concentrations for upper tract infections 1, 2
- Avoid in complicated UTIs or perinephric abscess 1
- Contraindicated in pregnancy during the last trimester (after 38 weeks gestation) 1
Common Pitfalls to Avoid
Wrong Pathogen Coverage
- Intrinsically resistant organisms: Do not use for Proteus species, Pseudomonas, or other organisms known to be resistant 4
- Nitrofurantoin works well for E. coli, Staphylococcus saprophyticus, and Enterococcus species 1
Wrong Clinical Context
- Never prescribe for suspected pyelonephritis—this is a critical error as the drug doesn't penetrate renal tissue adequately 2
- Avoid in patients with alkaline urine, as this reduces efficacy 4
Monitoring Failures
- Monitor for peripheral neuropathy, pulmonary reactions, and hepatotoxicity, especially in patients with borderline renal function 2
- Most common side effects are nausea and headache, with adverse event rates of 5.6-34% 1
Follow-Up Recommendations
When NOT to Order Follow-Up Testing
- Do not order routine post-treatment cultures if the patient is asymptomatic 1, 2
- Routine post-treatment urinalysis is not indicated for asymptomatic patients 1
When to Obtain Follow-Up Testing
- Obtain urine culture with susceptibility testing if:
- Retreatment strategy: Use a different antibiotic for 7 days, assuming resistance to nitrofurantoin 2
Alternative First-Line Options When Nitrofurantoin Cannot Be Used
If contraindications exist (renal impairment, suspected pyelonephritis, or patient intolerance):
- Fosfomycin trometamol 3 g single dose (slightly lower efficacy than nitrofurantoin) 1
- Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days (only if local E. coli resistance <20%) 1
- Pivmecillinam 400 mg twice daily for 5 days (where available) 1