From the Guidelines
For adults with uncomplicated urinary tract infections (UTIs), the recommended dose and frequency of Cephalexin (Keflex) is 500 mg orally every 12 hours or 250 mg orally every 6 hours for 7-14 days, with 7 days being most common for uncomplicated cases. This recommendation is based on the general guidelines for treating UTIs, although the specific study 1 does not provide detailed information on the dosage and frequency of Cephalexin. According to the study 1, beta-lactam agents, including Cephalexin, are less well studied but may be appropriate in certain settings, with inferior efficacy and more adverse effects compared to other UTI antimicrobials.
Key Considerations
- The study 1 recommends other antimicrobials, such as Nitrofurantoin monohydrate/macrocrystals and Trimethoprim-sulfamethoxazole, as first-line treatments for acute uncomplicated cystitis.
- Cephalexin may be considered an alternative antimicrobial for acute cystitis, especially when other recommended agents cannot be used.
- It is essential to complete the entire course of antibiotics, even if symptoms improve before finishing, and to drink plenty of water during treatment to help flush the urinary system.
- Common side effects of Cephalexin include diarrhea, nausea, and potential allergic reactions, especially in those with penicillin allergies.
Treatment Duration
- For uncomplicated UTIs, treatment with Cephalexin typically lasts for 7 days.
- For complicated UTIs, treatment may extend to 14 days.
- It is crucial to follow the recommended treatment duration and to consult a healthcare provider if symptoms do not improve within 2-3 days or if they worsen.
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 dose and frequency of Cephalexin (Keflex) for urinary tract infection (UTI) in adults is 500 mg every 12 hours for 7 to 14 days 2.
- The dosage may be adjusted based on the severity of the infection.
- For more severe infections, larger doses may be needed.
From the Research
Cephalexin Dosage for Urinary Tract Infections in Adults
- The recommended dose and frequency of Cephalexin for urinary tract infection (UTI) in adults can vary, but studies suggest the following:
- A dose of 500 mg twice daily (BID) or 500 mg four times daily (QID) can be effective for treating uncomplicated UTIs 3
- A study found no difference in treatment failure between patients treated with cephalexin 500 mg BID and those treated with 500 mg QID 3
- Another study suggested that twice-daily cephalexin is as effective as 4-times-daily dosing for uUTI, and may improve patient adherence 3
- Patients with creatinine clearances less than 30 ml/min may require a reduction in cephalexin dosage, proportional to the reduced function 4
- The choice of dosage regimen may depend on various factors, including the severity of the infection, the presence of underlying medical conditions, and the patient's renal function
- It is essential to note that cephalexin is not absorbed from the stomach but is totally and rapidly absorbed in the upper intestine, and its concentrations in urine can exceed 1000 mg/L after a small dose 4, 5
- Other studies have investigated the use of cephalexin in UTIs, including a study that found cephalexin to be effective in treating chronic urinary tract infections when administered orally at 12-hourly intervals 6