Children: 25–50 mg/kg/day in divided doses every 6–12 hours
Note: Adjust dose in renal impairment. Duration depends on infection severity.
Route of Administration
Oral (capsule, tablet, suspension)
Mechanism of Action
Cephalexin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins, leading to lysis and death. Active against many Gram-positive bacteria and some Gram-negative bacteria.
Common Adverse Effects
Diarrhea
Nausea, vomiting
Abdominal discomfort
Skin rash
Serious Adverse Effects
Anaphylaxis
Severe hypersensitivity reactions
Clostridioides difficile–associated diarrhea
Hepatic dysfunction (rare)
Contraindications
Hypersensitivity to cephalosporins
History of severe penicillin allergy
Precautions
Renal impairment (dose adjustment may be needed)
History of allergy or asthma
Monitor for diarrhea and signs of infection if prolonged use
Drug Interactions
Oral contraceptives – effectiveness may be reduced
Warfarin – may increase anticoagulant effect
Probenecid – decreases renal excretion of cephalexin
Pregnancy & Lactation
Generally considered safe in pregnancy and breastfeeding if used as prescribed.
Patient Counseling
Complete the full course of therapy
Take with or without food
Report rash, diarrhea, or allergic symptoms immediately