Cephalexin for UTI Prophylaxis
Cephalexin (Keflex) can be effectively used for urinary tract infection prophylaxis at a dose of 125-250 mg nightly, with evidence supporting its efficacy in preventing recurrent UTIs. 1
Evidence for Cephalexin in UTI Prophylaxis
The Journal of Urology guidelines specifically mention cephalexin as an effective prophylactic agent for recurrent UTIs:
- A study by Gower showed that cephalexin (125 mg nightly) significantly reduced UTIs compared to placebo during a 12-month follow-up period (p<0.01) 1
- Low-dose cephalexin (125-250 mg nightly) has been shown to be effective in preventing recurrent UTIs without promoting bacterial resistance 2
Dosing Recommendations
For UTI prophylaxis, the evidence supports:
- 125-250 mg once daily in the evening 1, 3
- Long-term studies have shown that 125 mg daily is as effective as 250 mg daily when given as a single evening dose 3
- This low-dose approach minimizes the risk of developing antimicrobial resistance 2
Advantages of Cephalexin for UTI Prophylaxis
- Minimal development of resistant E. coli in rectal and vaginal flora when used at prophylactic doses 2
- In a study of 23 women on 250 mg cephalexin nightly for 6 months, 22 remained infection-free with no development of resistant E. coli 2
- Good urinary penetration and bioavailability 4, 5
- Convenient once-daily dosing improves adherence 4, 3
Antibiotic Stewardship Considerations
While cephalexin is effective for UTI prophylaxis, antibiotic stewardship principles should be considered:
- Antibiotic prophylaxis should not be routinely prescribed but reserved for patients with recurrent UTIs (defined as three or more UTIs per year with positive cultures and symptoms) 1
- Before initiating prophylaxis, patients should be medically reviewed to determine appropriateness 1
- Long-term antibiotic use may contribute to resistance, though cephalexin at low doses has shown minimal development of resistance 1, 2
Alternative Approaches to UTI Prevention
Non-antibiotic approaches should be considered before initiating antibiotic prophylaxis:
- Adequate hydration (2-2.5 L/day) 1
- Proper hand and perineal hygiene 1
- Frequent bladder emptying 1
- Proper catheter use (if applicable) 1
Monitoring and Duration
- Monitor for UTI symptoms and adverse effects
- Consider periodic urine cultures to assess for breakthrough infections
- Prophylaxis duration typically ranges from 6-12 months 6
- After this period, reassess the need for continued prophylaxis
Cautions and Contraindications
- Cephalexin is not FDA-approved specifically for UTI prophylaxis, though it is indicated for genitourinary tract infections 7
- Patients with hypersensitivity to cephalosporins should avoid cephalexin
- Consider renal function when dosing, as cephalexin is primarily excreted unchanged in the urine 7
In summary, cephalexin is an effective option for UTI prophylaxis in patients with recurrent UTIs, with evidence supporting once-daily low-dose administration. Its favorable resistance profile at prophylactic doses makes it a good choice compared to other antibiotics like fluoroquinolones, which have more significant concerns regarding collateral damage and resistance.