Cephalexin (Keflex, Duricef)


  • Antibiotic


  • Cephalosporin, First Generation


  • Respiratory tract infections (S. pneumoniae, group A beta-hemolytic streptococci)

  • Otitis media (S. pneumoniae, H. influenzae, M. catarrhalis, staphylococci, streptococci)

  • Genitourinary tract infections (E. coli, Klebsiella species, Proteus mirabilis)

  • Skin, bone, and joint infections (staphylococci, streptococci, Proteus mirabilis)


  • Cross sensitivity with penicillin allergies


  • Pregnancy category B

  • Use with caution in patients with penicillin allergy (5-10% chance of cross-reactivity)

  • Counsel patient to finish all medication to prevent development of resistance

Adverse Reactions (Side Effects):

  • Hypersensitivity reactions

  • Gastrointestinal: nausea, vomiting, diarrhea

  • Vaginitis


  • Administered orally (capsules and oral suspension)

  • Adults:

    • 250mg every 6 hours (1-4 grams per day in divided doses)

    • Strep pharyngitis, skin and skin structure infections and uncomplicated cystitis in patients >15 years old: 500mg every 12 hours

  • Children:

    • Do not exceed adult dosing

    • Otitis media: 75-100mg/kg/day in 4 divided doses

    • Beta-hemolytic streptococcal infections: continue therapy for at least 10 days

    • For oral suspension:  refrigerate, shake well, good for 14 days only

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