From the Guidelines
Keflex (cephalexin) 500mg four times a day is generally considered a safe and standard dosage for adults with normal kidney function. This dosage, totaling 2000mg daily, is commonly prescribed for various bacterial infections including skin infections, respiratory tract infections, and urinary tract infections, as supported by the Infectious Diseases Society of America guidelines 1. The duration of treatment typically ranges from 7 to 14 days depending on the type and severity of infection. It's essential to take Keflex at evenly spaced intervals (approximately every 6 hours) to maintain consistent antibiotic levels in your bloodstream.
- Common side effects may include diarrhea, nausea, or stomach pain.
- If you develop a rash, severe diarrhea, or signs of an allergic reaction, contact your healthcare provider immediately.
- Always complete the full course of antibiotics even if you feel better before it's finished. This dosage may need adjustment for patients with kidney impairment, the elderly, or those with certain medical conditions, as indicated in the guidelines for the diagnosis and management of skin and soft tissue infections 1. Keflex works by disrupting bacterial cell wall synthesis, which ultimately kills the bacteria causing the infection.
- The recommended dosage for adults with normal kidney function is 500 mg every 6 hours, as stated in the guidelines 1.
- For patients with kidney impairment, the dosage may need to be adjusted, and the guidelines recommend a dosage of 250-500 mg every 8-12 hours 1. This dosage should only be taken as prescribed by your healthcare provider who has evaluated your specific condition.
From the FDA Drug Label
The adult dosage ranges from 1 to 4 g daily in divided doses. 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. If daily doses of cephalexin greater than 4 g are required, parenteral cephalosporins, in appropriate doses, should be considered.
The dosage of Keflex (cephalexin) 500mg four times a day is within the recommended daily dose range of 1 to 4 g. This dosage is safe as long as the total daily dose does not exceed 4 g. 2
- Key points:
- Daily dose range: 1 to 4 g
- Dosage frequency: every 6 hours (usual adult dose) or every 12 hours (for specific infections)
- Maximum daily dose: 4 g
- Important consideration: If daily doses greater than 4 g are required, alternative treatment options should be considered.
From the Research
Dosage Information
- The standard dosage of Keflex (cephalexin) can vary depending on the infection being treated, with typical doses ranging from 250mg to 500mg, taken 2 to 4 times a day 3.
- For patients with creatinine clearances less than 30 ml/min, a reduction in cephalexin dosage is required, proportional to the reduced function 3.
Safety and Efficacy
- Studies have shown that cephalexin 500mg four times a day is effective in treating urinary tract infections (UTIs), with no significant difference in treatment failure rates compared to twice-daily dosing 4, 5.
- Cephalexin has a low incidence of side effects and is generally well-tolerated, with most adverse events being mild and transient 3, 4, 5.
Comparison of Dosage Regimens
- A study comparing twice-daily and four-times-daily cephalexin dosing for the treatment of uncomplicated UTIs found no difference in treatment failure rates between the two groups 4.
- Another study found that twice-daily cephalexin dosing was as effective as four-times-daily dosing for the treatment of UTIs, with no significant difference in treatment failure rates or adverse events 5.