What is the recommended dose of Keflex (cephalexin) for a male with a urinary tract infection (UTI)?

Cephalexin Dosing for Male Urinary Tract Infection

The recommended dose of Keflex (cephalexin) for a male with urinary tract infection is 500 mg orally every 12 hours for 7-14 days.

Dosing Rationale

Cephalexin is an appropriate antibiotic choice for male UTIs based on several key factors:

• The FDA-approved dosing for cephalexin indicates 500 mg every 12 hours is appropriate for uncomplicated cystitis, with a recommended duration of 7-14 days 1
• Males with UTIs are classified as having complicated UTIs according to the European Association of Urology guidelines, as male gender is a complicating factor 2
• First-generation cephalosporins like cephalexin achieve high urinary concentrations (500-1000 μg/mL following 250-500 mg doses), which is many times greater than the minimum inhibitory concentration for common urinary pathogens 3

Duration of Therapy

For male UTIs, a longer duration is typically recommended compared to uncomplicated UTIs in women:

• 7-14 days is the appropriate duration for complicated UTIs 4
• Male UTIs are considered complicated by definition 2
• Recent research suggests 7 days may be sufficient for many male UTIs, but the traditional recommendation has been 7-14 days 2

Dosing Schedule Options

Recent evidence supports twice-daily dosing of cephalexin for UTIs:

• A 2023 study demonstrated that cephalexin 500 mg twice daily was as effective as 500 mg four times daily for the treatment of uncomplicated UTIs, with no significant difference in treatment failure rates (12.7% vs 17%, p=0.343) 5
• Another study showed that cephalexin 1 g twice daily was as effective as when given four times daily for urinary tract infections 6
• Twice-daily dosing may improve patient adherence compared to more frequent dosing regimens 5

Alternative Dosing Considerations

For severe infections or resistant organisms:

• The daily dose of cephalexin can be increased up to 4 g per day in divided doses 1
• For severe infections, the dosage may be doubled 1
• If daily doses greater than 4 g are required, parenteral cephalosporins should be considered 1

Monitoring and Follow-up

• Urine culture with susceptibility testing should be obtained if symptoms don't resolve by the end of treatment or recur within 2 weeks 4
• Patients with creatinine clearance less than 30 mL/min require a reduction in cephalexin dosage proportional to the reduced renal function 3

Common Pitfalls to Avoid

1. Inadequate duration: Treating male UTIs with the shorter durations used for uncomplicated female UTIs (3-5 days) may lead to treatment failure
2. Failure to obtain cultures: Always obtain urine cultures in males with suspected UTIs to guide therapy
3. Overlooking anatomical abnormalities: Male UTIs often have underlying anatomical or functional abnormalities that may require further evaluation
4. Inadequate dosing: Ensure adequate dosing based on infection severity and patient factors

Cephalexin remains a valuable option for male UTIs due to its excellent urinary penetration, good safety profile, and efficacy against common uropathogens when susceptibility is confirmed.