What is considered a high dose of Cephalexin (Keflex)?

From the Guidelines

High dose Keflex (cephalexin) is generally considered to be above 500 mg per dose, with a maximum daily dose of 4 grams or more for adults, and above 20 mg per kg per dose for children, as indicated in the most recent guideline update 1. The typical adult dosing range for Keflex is 1-4 grams daily, divided into 2-4 doses, with 4 grams being at the upper limit of standard therapy. For severe infections, doses may reach up to 6 grams daily in divided doses, which would definitely be considered high dose. Some key points to consider when prescribing high dose Keflex include:

• Monitoring for side effects which may be more common at higher doses, including gastrointestinal disturbances (nausea, vomiting, diarrhea), allergic reactions, and potential nephrotoxicity.
• Patients with reduced kidney function require dose adjustments to prevent drug accumulation.
• High dose Keflex is typically reserved for more severe infections or those caused by less susceptible organisms, as the higher concentration of the antibiotic helps overcome bacterial resistance mechanisms and achieves better penetration into infected tissues. According to the most recent guideline update, the recommended dose for children is 20 mg per kg per dose twice daily, with a maximum of 500 mg per dose, for 10 days 1. It's also important to note that the dosage recommendations may vary depending on the specific infection being treated and the patient's individual needs, as outlined in the guidelines for managing group A streptococcal pharyngitis 1. In general, high dose Keflex should be used with caution and under close medical supervision to minimize the risk of adverse effects and ensure optimal treatment outcomes.

From the FDA Drug Label

For more severe infections or those caused by less susceptible organisms, larger doses may be needed If daily doses of cephalexin greater than 4 g are required, parenteral cephalosporins, in appropriate doses, should be considered.

• High dose of Keflex (cephalexin) is considered to be greater than 4 g per day 2.
• The usual adult dose is 250 mg every 6 hours, but for more severe infections, larger doses may be needed.
• In severe infections, the dosage may be doubled.

From the Research

High Dose Keflex

• The definition of a high dose of Keflex (cephalexin) is not explicitly stated in the provided studies, but the dosages used in the studies can be considered as follows:
  • 500 mg every 6 hours 3
  • 250 mg four times daily (QID) 4
  • 500 mg QID 5
  • 1,500-2,000 mg/day 6
• These dosages can be considered as standard or moderate doses, and a high dose would likely be higher than these ranges.
• However, it's essential to note that the dosage of cephalexin should be determined by a healthcare professional based on the individual patient's needs and medical condition.

Dosage Comparison

• The studies compared the efficacy and safety of cephalexin with other antibiotics, such as ofloxacin 3 and cefdinir 4, 5.
• The results showed that cephalexin was effective in treating skin and skin-structure infections, with cure rates ranging from 83% to 90% 4, 5, 7.
• The studies also reported that cephalexin was well-tolerated, with mild and infrequent side effects 3, 4, 5, 7.

Clinical Use

• Cephalexin is commonly used to treat streptococcal and staphylococcal skin infections, including abscesses, wound infections, and cellulitis 3, 4, 5, 7.
• The antibiotic is also effective in treating methicillin-susceptible Staphylococcus aureus (MSSA)-induced bacteremic vertebral osteomyelitis, with a treatment success rate of 87% 6.