Spectrum of Activity


General Information

  • Uncomplicated skin and soft tissue infection
  • MSSA infections (non-bacteremic)
  • Uncomplicated cystitis
  • Allergy/rash (immediate or delayed)
  • Dermatologic reactions including erythema multiform, Steven-Johnson Syndrome (rare) and Toxic Epidermal Necrolysis (rare)
  • Positive Coombs
  • Cytopenias
  • Eosinophilia
  • CNS effects including agitation, hallucinations, confusion, fatigue, headache, dizziness
  • Hepatic & renal laboratory abnormalities
  • GI disturbances (diarrhea, nausea)
  • Arthralgia, arthropathy
  • Interstitial Nephritis (rare)
  • Increases metformin levels

  • May enhance anticoagulant effect of Vitamin K antagonists (including warfarin)

  • Some vitamins/minerals may reduce absorption/levels of cephalexin

Cefazolin susceptibility predicts cephalexin susceptibility for most organisms; however, cephalexin may not be appropriate for severe infections or bacteremia.

Antimicrobial class: First Generation Cephalosporin

Pregnancy category: B

Average Serum half life: 0.5-1.2hr (longer with renal impairment)

Biliary penetration: Moderate

CSF penetration: Poor

Lung penetration: Moderate

Urine penetration: Therapeutic