From the Guidelines
For uncomplicated urinary tract infections (UTIs), the recommended dose of Keflex (cephalexin) is typically 500 mg orally every 12 hours or 250 mg orally every 6 hours for 7-14 days, with most uncomplicated cases requiring only 7 days of treatment. The medication should be taken with food to reduce stomach upset, and patients should complete the entire course even if symptoms improve before finishing. It's essential to drink plenty of water while taking this antibiotic to help flush the urinary system. Keflex works by inhibiting bacterial cell wall synthesis, which is effective against many common UTI-causing bacteria, particularly E. coli. Patients should be aware that common side effects may include diarrhea, nausea, and potential yeast infections. Those with known allergies to cephalosporin antibiotics or penicillins should inform their healthcare provider before taking Keflex. If symptoms worsen or don't improve within 2-3 days of starting treatment, medical advice should be sought. According to the most recent guidelines, such as those from the American College of Physicians 1, the use of short-course antibiotics is recommended for uncomplicated UTIs, but cephalexin is not the first-line treatment due to its lower efficacy compared to other options like nitrofurantoin, trimethoprim-sulfamethoxazole, or fosfomycin. However, it may still be considered in certain cases, as suggested by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases guidelines 1.
Some key points to consider when prescribing cephalexin for UTIs include:
- The patient's medical history and potential allergies to cephalosporins or penicillins
- The severity of the infection and the presence of any complicating factors
- The local resistance patterns of common UTI-causing bacteria
- The potential for adverse effects, such as diarrhea, nausea, and yeast infections
- The importance of completing the full course of treatment, even if symptoms improve before finishing.
It's also important to note that the 2021 guidelines from the American College of Physicians 1 recommend short-course antibiotics for uncomplicated UTIs, but cephalexin is not the first-line treatment due to its lower efficacy compared to other options. However, the guidelines do suggest that cephalexin may still be considered in certain cases, as supported by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases guidelines 1.
From the FDA Drug Label
Adults: The adult dosage ranges from 1 to 4 g daily in divided doses. The usual adult dose is 250 mg every 6 hours. For the following infections, a dosage of 500 mg may be administered every 12 hours: streptococcal pharyngitis, skin and skin structure infections, and uncomplicated cystitis in patients over 15 years of age Cystitis therapy should be continued for 7 to 14 days.
The recommended dose of Keflex (Cephalexin) for an uncomplicated urinary tract infection (UTI) is 500 mg every 12 hours for 7 to 14 days in patients over 15 years of age 2.
From the Research
Keflex Dose for UTI
The recommended dose of Keflex (Cephalexin) for an uncomplicated urinary tract infection (UTI) can vary.
- A study published in 2023 3 compared the effectiveness of cephalexin 500 mg twice daily (BID) and 500 mg four times daily (QID) for the treatment of uncomplicated urinary tract infections in females. The results showed that twice-daily cephalexin is as effective as 4-times-daily dosing for uUTI.
- Another study from 1975 4 found that a single dose of cephalexin 125 mg was as effective as a single dose of 250 mg given in the evening for the long-term treatment of urinary tract infection.
- However, these studies do not provide a clear recommendation for the optimal dose of Keflex for UTI.
- It's worth noting that other antibiotics, such as ciprofloxacin, have been studied for the treatment of UTI, and the minimum effective dose has been determined to be 100 mg BID for 3 days 5.
- Other cephalosporins, such as cefixime, have also been studied for the treatment of UTI, and the recommended dose is 200 mg twice daily 6.
- For children, a 3-day course of cephalexin, 25-50 mg/kg body weight per day, has been shown to be effective for the treatment of lower urinary tract infections 7.