What is the dosage and treatment protocol for Cephalexin (cephalexin)?

From the Guidelines

Cephalexin is typically prescribed at 250-500 mg orally every 6 hours for adults, with dosing adjusted based on infection severity, as recommended by the Infectious Diseases Society of America in their 2014 guidelines 1. For most common infections like skin infections or urinary tract infections, the standard regimen is 500 mg every 12 hours for 7-10 days.

• Children's dosing is weight-based, usually 25-50 mg/kg/day divided into four equal doses, as outlined in the guidelines 1.
• For severe infections, adult dosing may increase to 4 grams daily.
• Cephalexin should be taken with food if stomach upset occurs, though it can be taken with or without food.
• The full prescribed course should always be completed, even if symptoms improve before finishing. Cephalexin works by inhibiting bacterial cell wall synthesis, making it effective against many gram-positive bacteria and some gram-negative organisms.
• Common side effects include diarrhea, nausea, and skin rash.
• Those with penicillin allergies should use caution as cross-reactivity can occur.
• Patients should inform their healthcare provider about all medications they take, as cephalexin may interact with certain drugs like probenecid or metformin. The most recent and highest quality study, published in 2014 by the Infectious Diseases Society of America 1, provides the basis for these recommendations, prioritizing morbidity, mortality, and quality of life as the primary outcomes.
• The guidelines emphasize the importance of adjusting dosing based on infection severity and patient response.
• They also highlight the need for careful consideration of potential interactions with other medications and the risk of cross-reactivity in patients with penicillin allergies.

From the FDA Drug Label

Adults The adult dosage ranges from 1 to 4 g daily in divided doses. The 333 mg and 750 mg strengths should be administered such that the daily dose is within 1 to 4 grams per day. 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. 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. Pediatric Patients The usual recommended daily dosage for pediatric patients is 25 to 50 mg/kg in divided doses For streptococcal pharyngitis in patients over 1 year of age and for skin and skin structure infections, the total daily dose may be divided and administered every 12 hours.

The dosage of Cephalexin for adults is 1 to 4 g daily in divided doses, with a usual adult dose of 250 mg every 6 hours. For certain infections, such as streptococcal pharyngitis, skin and skin structure infections, and uncomplicated cystitis, a dosage of 500 mg may be administered every 12 hours. The treatment protocol for cystitis should be continued for 7 to 14 days. For pediatric patients, the usual recommended daily dosage is 25 to 50 mg/kg in divided doses. In severe infections, the dosage may be doubled 2.

• Key points for dosage and treatment protocol:
  • Adult dosage: 1 to 4 g daily in divided doses
  • Pediatric dosage: 25 to 50 mg/kg in divided doses
  • Treatment duration for cystitis: 7 to 14 days
  • Dosage for severe infections: may be doubled

From the Research

Dosage and Treatment Protocol for Cephalexin

• The dosage and treatment protocol for cephalexin vary depending on the type of infection being treated and the patient's age and renal function 3, 4, 5, 6.
• For adults, the typical dosage of cephalexin for urinary tract infections is 250-500 mg every 6-8 hours 3.
• For children, the dosage of cephalexin is typically higher per kilogram of body weight than for adults, and may need to be adjusted based on the child's age and renal function 3, 4.
• Twice-daily (BID) and thrice-daily (TID) dosing regimens of cephalexin have been proposed for the treatment of methicillin-susceptible Staphylococcus aureus (MSSA) infections in children, with doses ranging from 15-45 mg/kg per dose 4.
• For the treatment of skin and skin-structure infections, cephalexin 500 mg every 6 hours has been shown to be effective, although cefdinir 300 mg twice daily may be a suitable alternative 7.
• Patients with creatinine clearances less than 30 ml/min may require a reduction in cephalexin dosage, which should be proportional to the reduced renal function 3.

Special Considerations

• Cephalexin is not absorbed from the stomach, but is totally and rapidly absorbed in the upper intestine 3.
• Cephalexin does not penetrate into host tissue cells, which may account for its low incidence of side effects 3.
• Cephalexin is rapidly cleared from the body by the kidneys, with 70-100% of the dose excreted in the urine within 6-8 hours 3.
• The duration of treatment with cephalexin may vary depending on the type and severity of the infection, as well as the patient's response to treatment 5, 6.