Cephalexin (Keflex®) for UTIs (Uncomplicated)

Based on "Principles and Practice of Infectious Diseases"
written by John E. Bennett, MD

The most common type of Urinary Tract Infections (UTIs) is acute uncomplicated cystitis (bladder infection). Cystitis occurs mainly in women.

Recently cephalexin has fallen out of favour as a recommended treatment option for UTI due to increasing resistance of E. coli1.



  • Cephalexin (Keflex) is FDA approved for the treatment of UTIs.
  • Cephalexin reaches high urinary concentrations.
  • Suitable antibiotic for UTI in children3, cystitis during pregnancy2.
  • May be used for prophylaxis of cystitis after sexual intercourse5.
  • Generally well tolerated.
  • Cheap and widely available.


  • Relatively poor efficacy because of high resistance rates among E. coli to cephalexin.

Cephalexin Dosage for UTI

Tretment of uncomplicated infection: 250 mg 4 times daily for 7 days.

Prophylaxis of recurrent UTIs: postcoital (within 2 hours of sexual intercourse) cephalexin 250 mg5.

Clinical characteristics of infection and antimicrobial susceptibility patterns may differ from country to country.

Can Cephalexin treat UTI?

Cephalexin can treat uncomplicated urinary infection caused by susceptible bacteria. Decades ago cephalexin was very effective treatment4. Now this antibiotic has lost its usefulness due to the emerging resistance of uropathogens.

Cephalexin is not suitable as an empiric therapy for uncomplicated UTI, but can be used if urine culture shows susceptibility.

Note: Clinical characteristics of infection and antimicrobial susceptibility patterns may differ from country to country.

Is Cephalexin a good choice for UTI?

In the past cephalexin was among the first line options. But increasing resistance has limited its effectiveness.

Further reading


  • 1. Gupta K, Hooton TM, Naber KG, et al. International clinical practice guidelines for the treatment of acute uncomplicated cystitis and pyelonephritis in women: a 2010 update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases. Clin Infect Dis. 2011;52(5):e103–e120.
  • 2. Delzell JE Jr, Lefevre ML. Urinary tract infections during pregnancy. Am Fam Physician. 2000 Feb 1;61(3):713-21. Available at American Academy of Family Physicians
  • 3. Butler CC, O'Brien K, Wootton M, DUTY Study Team. Empiric antibiotic treatment for urinary tract infection in preschool children: susceptibilities of urine sample isolates. Fam Pract. 2016 Apr;33(2):127-32.
  • 4. Menday AP. Comparison of pivmecillinam and cephalexin in acute uncomplicated urinary tract infection. Int J Antimicrob Agents. 2000 Jan;13(3):183-7.
  • 5. Dason S, Dason JT, Kapoor A. Guidelines for the diagnosis and management of recurrent urinary tract infection in women. Can Urol Assoc J. 2011 Oct;5(5):316-22.

Published: August 01, 2018 by eMedExpert staff
Last updated: August 01, 2018



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