What is the recommended duration of Cephalexin (Keflex) treatment for a urinary tract infection (UTI)?

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Last updated: April 23, 2025View editorial policy

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From the FDA Drug Label

For the following infections, a dosage of 500 mg may be administered every 12 hours: ... and uncomplicated cystitis in patients over 15 years of age. Cystitis therapy should be continued for 7 to 14 days. The recommended duration of Keflex (cephalexin) for a urinary tract infection (UTI) is 7 to 14 days 1.

  • The dosage for uncomplicated cystitis is 500 mg every 12 hours.
  • The treatment duration may vary depending on the severity of the infection and the patient's response to therapy.

From the Research

Keflex (cephalexin) is typically prescribed for 5 days for uncomplicated urinary tract infections (UTIs). The standard adult dosage is 500 mg taken orally every 12 hours, or 250 mg every 6 hours 2. For more severe infections, the dose may be increased to 1 gram every 12 hours. It's essential to complete the entire prescribed course of antibiotics even if symptoms improve before finishing the medication. Keflex works by inhibiting bacterial cell wall synthesis, effectively killing the bacteria causing the infection. While taking Keflex, patients should drink plenty of water to help flush bacteria from the urinary tract and take the medication with food if stomach upset occurs. If symptoms don't improve within 2-3 days or worsen at any point, patients should contact their healthcare provider as this may indicate the infection is resistant to Keflex or another condition is present.

Some key points to consider when prescribing Keflex for UTIs include:

  • The increasing incidence of antimicrobial resistance among common uropathogens, which may affect treatment outcomes 2, 3, 4, 5, 6
  • The importance of selecting an antibiotic based on the patient's individual risk profile, prior antibiotic treatment, and local susceptibility patterns 2, 6
  • The need to await susceptibility testing results whenever possible to guide antibiotic therapy 3, 6
  • The potential for ecological adverse effects (collateral damage) of antimicrobial therapy, which should be considered when choosing an antibiotic 6

Overall, the treatment of UTIs with Keflex should be guided by the most recent and highest-quality evidence, with consideration of individual patient factors and local resistance patterns.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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