From the FDA Drug Label
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. The recommended dose of cephalexin for treating cellulitis (a type of skin and skin structure infection) is 500 mg every 12 hours 1.
- The dose may be adjusted based on the severity of the infection.
- For more severe infections, larger doses may be needed.
- If daily doses of cephalexin greater than 4 g are required, parenteral cephalosporins should be considered.
From the Research
The recommended dose of cephalexin for treating cellulitis is 1000 mg taken orally four times daily for 7 days, as this high-dose regimen has been shown to have fewer treatment failures compared to the standard dose of 500 mg four times daily, although it may be associated with a higher proportion of minor adverse effects. This recommendation is based on the most recent and highest quality study available, which was a pilot randomized controlled trial conducted in 2023 2. The study found that treatment failure occurred in 12.9% of patients in the standard-dose arm versus 3.2% in the high-dose arm, suggesting that the high-dose regimen may be more effective in treating cellulitis. However, it is essential to note that the high-dose regimen was also associated with a higher proportion of minor adverse effects. In clinical practice, the decision to use the high-dose regimen should be made on a case-by-case basis, taking into account the severity of the infection, the patient's medical history, and the potential risks and benefits of the treatment. Other studies have also investigated the use of cephalexin in treating cellulitis, but they are either older or have limitations that make them less relevant to current clinical practice 3, 4, 5, 6. For example, a study from 2006 compared the efficacy and safety of cefdinir to cephalexin in adolescents and adults with mild to moderate uncomplicated skin and skin structure infections, but it did not specifically address the optimal dose of cephalexin for treating cellulitis 4. Another study from 2013 compared the effectiveness of cephalexin plus trimethoprim-sulfamethoxazole versus cephalexin alone for treating uncomplicated cellulitis, but it did not investigate the use of high-dose cephalexin 5. Therefore, the recommendation to use 1000 mg of cephalexin four times daily for 7 days is based on the most recent and highest quality evidence available. It is crucial to follow the recommended treatment guidelines and to consult with a healthcare provider to determine the best course of treatment for each individual patient. Some key points to consider when treating cellulitis with cephalexin include:
- The importance of completing the full course of antibiotics, even if symptoms improve before completion
- The potential for minor adverse effects, such as diarrhea and nausea, and the need to monitor patients for these effects
- The importance of adjusting the dose and duration of treatment based on the severity of the infection and the patient's medical history
- The need to consider alternative treatments, such as other antibiotics or supportive care, in patients who do not respond to cephalexin or who experience adverse effects.