Will Keflex (cephalexin) cover bacterial pharyngitis?

Keflex (Cephalexin) for Bacterial Pharyngitis

Yes, Keflex (cephalexin) is an appropriate treatment option for bacterial pharyngitis, particularly in penicillin-allergic patients who do not have anaphylactic-type hypersensitivity reactions. 1, 2

First-Line vs. Alternative Treatment

First-Line Treatment

• Penicillin or amoxicillin remains the first-line treatment for Group A Streptococcal (GAS) pharyngitis due to:
  • Narrow spectrum of activity
  • Infrequent adverse reactions
  • Modest cost
  • Proven efficacy 2

When to Use Cephalexin

• Cephalexin is recommended as an alternative treatment in:
  • Patients with non-anaphylactic penicillin allergy 1, 2
  • Cases where compliance with penicillin might be an issue

Dosing and Duration

• For GAS pharyngitis, cephalexin should be administered for a full 10-day course 1, 2
• Recommended dosing:
  • Adults: 500 mg 2-3 times daily for 10 days 2
  • Children: 20 mg/kg twice daily (maximum 500 mg per dose) for 10 days 2
  • Total daily dose of approximately 30 mg/kg has been shown effective 3

Efficacy of Cephalexin

• Cephalexin has demonstrated effectiveness against Streptococcus pyogenes (Group A Strep) 4
• Clinical studies show bacteriologic cure rates of 92-93% for GAS pharyngitis 5, 6
• Some studies suggest cephalexin may have slightly better efficacy than penicillin with:
  • Lower clinical failure rates (3% vs 8% for penicillin)
  • Lower bacteriologic failure rates (7% vs 11% for penicillin) 6

Important Considerations and Cautions

Cross-Reactivity with Penicillin Allergy

• Up to 10% of penicillin-allergic individuals may also be allergic to cephalosporins 1
• Cephalexin should NOT be used in patients with immediate (anaphylactic-type) hypersensitivity to penicillin 1

Alternative Options for Severe Penicillin Allergy

For patients with anaphylactic penicillin allergy, consider:

• Clindamycin (7 mg/kg three times daily, max 300 mg per dose) for 10 days 1, 2
• Macrolides (clarithromycin) for 10 days 1
• Azithromycin (12 mg/kg once daily, max 500 mg) for 5 days 1, 2

Dosing Schedule

• Both twice-daily (BID) and four-times-daily (QID) regimens of cephalexin have shown similar efficacy 3, 5
• BID dosing may improve adherence to the full treatment course

Adjunctive Therapy

• For symptom relief, consider:
  • Ibuprofen (preferred): 400 mg every 6-8 hours as needed 2
  • Acetaminophen: 500-1000 mg every 4-6 hours as needed 2
• Avoid aspirin in children due to risk of Reye syndrome 1, 2

Treatment Duration Importance

• The full 10-day course is critical to:
  • Prevent acute rheumatic fever
  • Ensure complete eradication of the organism
  • Prevent recurrence

Clinical Pearls

• Patients are generally considered non-contagious after 24 hours of antibiotic therapy 2
• Symptoms typically improve within 24-48 hours after starting treatment 2
• Narrow-spectrum cephalosporins like cephalexin are preferred over broader-spectrum options to minimize development of antibiotic resistance 1