From the Guidelines
The typical dosage of cephalexin is 20 mg per kg per dose twice daily, with a maximum of 500 mg per dose, as recommended for patients with penicillin allergy. This dosage is based on the strongest and most recent evidence available, specifically the IDSA updates guideline for managing group A streptococcal pharyngitis 1. The following key points are essential to consider:
- The dosage is calculated based on the patient's weight, with a maximum dose of 500 mg per dose.
- The treatment duration is typically 10 days, as specified in the guideline.
- It is crucial to complete the full course of antibiotics, even if symptoms improve before the medication is finished, to ensure the infection is completely eliminated and to prevent antibiotic resistance.
- Cephalexin works by interfering with bacterial cell wall synthesis, causing the bacteria to rupture and die.
- Common side effects may include diarrhea, nausea, and skin rash, and patients with a history of allergic reactions to penicillins or other cephalosporins should use caution as cross-sensitivity can occur. In comparison to other guidelines, such as the pediatric community pneumonia guidelines 2, the recommended dosage of cephalexin may vary depending on the specific infection being treated and the patient's age and weight. However, the IDSA guideline provides the most recent and strongest evidence for the typical dosage of cephalexin, making it the most reliable source for clinical decision-making. Some key differences between the guidelines include:
- The pediatric community pneumonia guidelines recommend a dosage of 75-100 mg/kg/day in 3 or 4 doses for oral cephalexin, which is higher than the recommended dosage in the IDSA guideline.
- The IDSA guideline provides a clear recommendation for the treatment of group A streptococcal pharyngitis, whereas the pediatric community pneumonia guidelines provide recommendations for a broader range of infections.
From the FDA Drug Label
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: The usual recommended daily dosage for pediatric patients is 25 to 50 mg/kg in divided doses
The typical dosage of cephalexin per dose is:
- 250 mg for adults every 6 hours
- 500 mg for adults every 12 hours for certain infections
- 25-50 mg/kg in divided doses for pediatric patients 3
From the Research
Cephalexin Dosage
- The typical dosage of cephalexin per dose is 500 mg, administered twice or thrice daily 4.
- This dosage is similar to cefadroxil, which is also administered at 500 mg twice daily 4.
- Cephalexin can be used as a fluoroquinolone-sparing alternative for the treatment of uncomplicated lower urinary tract infections (uLUTIs) 4.
Comparison with Other Antibiotics
- Cephalexin has been compared to other orally administered cephalosporins, such as cefaclor, cefdinir, cefpodoxime, cefprozil, and cefuroxime axetil, in terms of antimicrobial spectrum and potency 5.
- Cephalexin was found to be among the least potent and have the narrowest antimicrobial spectrum against the pathogens evaluated 5.
Treatment Duration
- Recent studies have investigated the use of shorter treatment durations for common infections, including community-acquired pneumonia, intraabdominal sepsis, gram-negative bacteraemia, and vertebral osteomyelitis 6.
- However, the optimal treatment duration for cephalexin has not been specifically addressed in these studies 6.