What is the recommended dosing of cephalexin (cephalexin) for the treatment of a felon?

Cephalexin Dosing for Felon

For the treatment of a felon (finger pulp infection), administer cephalexin 500 mg orally four times daily (every 6 hours) for 7-10 days in adults, as this provides effective coverage against Staphylococcus aureus and Streptococcus species, the primary pathogens in these infections. 1, 2

Adult Dosing Regimen

• The standard dose is 500 mg orally four times daily (every 6 hours) for skin and soft tissue infections caused by methicillin-susceptible Staphylococcus aureus (MSSA), which is the most common pathogen in felons 1, 2

• The FDA-approved dosing range for adults is 1-4 grams daily in divided doses, with 250 mg every 6 hours being the usual adult dose, though 500 mg every 6 hours is preferred for skin and soft tissue infections 2

• For more severe infections or those caused by less susceptible organisms, larger doses may be needed, but if daily doses greater than 4 grams are required, parenteral cephalosporins should be considered 2

Duration of Therapy

• Treatment should continue for 7-10 days depending on clinical response, with the typical duration for uncomplicated skin infections being 7 days 1, 3

• If the infection has not improved within 5 days, treatment should be extended 3

Pediatric Dosing (if applicable)

• For children, the recommended dose is 75-100 mg/kg/day divided into 3-4 doses for MSSA infections 4, 1

• The usual pediatric dosage ranges from 25-50 mg/kg/day in divided doses for mild to moderate infections, with a maximum daily dose of 4000 mg 4, 2

Critical Clinical Considerations

MRSA Coverage Limitation

• Cephalexin is completely ineffective against MRSA - if methicillin-resistant Staphylococcus aureus is suspected or confirmed (particularly in patients with risk factors such as recent hospitalization, injection drug use, or prior MRSA infection), alternative agents such as trimethoprim-sulfamethoxazole or clindamycin must be used instead 1, 3

When Surgical Drainage is Essential

• A felon requires incision and drainage as the primary treatment modality - antibiotics alone are insufficient 5

• Studies demonstrate that after adequate surgical drainage of skin and soft tissue abscesses, clinical cure rates exceed 90% even without antibiotics, though antibiotics are still recommended for felons due to the closed space nature of the infection 5

Monitoring for Treatment Failure

• If systemic signs of infection develop (fever, ascending lymphangitis, spreading cellulitis) or if there is no improvement within 48-72 hours, consider broadening antimicrobial coverage or reassessing for inadequate drainage 3

Common Pitfalls to Avoid

• Do not use cephalexin as monotherapy if MRSA is suspected - community-acquired MRSA now accounts for the majority of skin and soft tissue infections in many regions, with one study showing 87.8% of S. aureus isolates being MRSA 5

• Do not rely on antibiotics alone without ensuring adequate surgical drainage of the felon - the closed compartment nature of this infection requires decompression 5

• Avoid using cephalexin in patients with a history of immediate hypersensitivity reactions (anaphylaxis, angioedema, urticaria) to penicillins, as cross-reactivity can occur 3