Nitrofurantoin for UTIs in Men
Nitrofurantoin can be used for uncomplicated lower urinary tract infections in men, but only when systemic symptoms and prostate involvement are clearly absent—otherwise, a fluoroquinolone or other tissue-penetrating antibiotic should be used instead.
Key Limitation: Poor Tissue Penetration
The fundamental problem with nitrofurantoin in men is that it achieves low blood and tissue concentrations, making it ineffective for prostate involvement 1, 2. This is critical because:
- Approximately 27% of men treated with nitrofurantoin require retreatment within 60-90 days, suggesting either treatment failure or unrecognized prostatic involvement 2
- The frequency of occult prostate involvement in men presenting with apparent "simple cystitis" remains unknown 1
- Unrecognized tissue involvement leads to breakthrough infections despite treatment 2
When Nitrofurantoin IS Appropriate in Men
Nitrofurantoin may be used when all of the following criteria are met:
- No systemic symptoms (no fever, no rigors, no severe malaise) 1
- No signs of prostatitis (no perineal pain, no obstructive voiding symptoms, no tender prostate on exam) 1
- No upper tract involvement (no flank pain, no costovertebral angle tenderness) 3
- Normal renal function (contraindicated in any degree of renal impairment) 4
Recommended Approach for Men with UTI
For uncomplicated lower UTI without systemic symptoms:
- Nitrofurantoin 100 mg twice daily for 5-7 days 5, 6
- Alternative first-line: trimethoprim-sulfamethoxazole (if local resistance patterns allow) 3, 5
For any concern about prostate or upper tract involvement:
- Ciprofloxacin is preferred as it achieves adequate tissue penetration 3
- For mild-to-moderate prostatitis/pyelonephritis: ciprofloxacin (if resistance patterns allow) 3
- For severe upper tract infection: ceftriaxone or cefotaxime 3
Clinical Pitfalls to Avoid
The major risk is undertreating occult prostatitis or upper tract infection 2. Red flags that should prompt you to avoid nitrofurantoin include:
- Any fever or systemic symptoms 1
- Recurrent UTIs in the same patient 3
- Obstructive voiding symptoms 1
- Age >65 years (higher risk of prostatic involvement)
- Recent UTI within 3 months
Balancing Antimicrobial Stewardship
While fluoroquinolones have better tissue penetration, their overuse drives resistance and causes collateral microbiome damage 5, 1. The oral alternative to nitrofurantoin is ciprofloxacin, but this is undesirable due to side effects, microbiome disturbance, and resistance development 1.
Therefore, nitrofurantoin remains valuable for carefully selected men with clear-cut lower UTI without any features suggesting tissue invasion 1. The number of men developing urosepsis during nitrofurantoin treatment is likely outweighed by the large number of successful prescriptions 1.
Guideline Consensus
The WHO 2024 guidelines list nitrofurantoin as first-choice for lower urinary tract infections generally, but specifically recommend ciprofloxacin for prostatitis 3. This distinction is crucial—the guidelines do not differentiate male versus female patients for lower UTI, but the anatomical reality of the prostate creates a unique challenge in men that requires clinical judgment 3, 1.
Bottom line: Use nitrofurantoin in men only when you are confident the infection is limited to the bladder, with no systemic symptoms and no prostatic involvement. When in doubt, use a fluoroquinolone or beta-lactam with better tissue penetration.