Skip to content
ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
First-Generation Cephalosporin — Skin / Soft Tissue / UTI

Cefalexin

Brand names: Ceporex, Keflex

Used in: Urinary Tract Infection

Cefalexin is a first-generation oral cephalosporin used for urinary, respiratory, and skin and soft-tissue infections, and as an alternative where a penicillin is unsuitable in some situations.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

A beta-lactam antibiotic that inhibits bacterial cell-wall synthesis by binding penicillin-binding proteins.

Prescribing in practice

  • Use caution in penicillin allergy — cross-reactivity is low but more relevant with previous immediate or severe reactions.
  • Reduce the dose in significant renal impairment.
  • Like other antibiotics it can disturb gut flora and predispose to Clostridioides difficile infection.

Monitoring

Short courses need no routine monitoring; review clinical response and adverse effects.

Counselling the patient

  • Complete the prescribed course.
  • Report a rash, or severe or prolonged diarrhoea.

Evidence & guidelines

Used per local antimicrobial guidance for the indications above.

Reference: NICE CG121 (Cellulitis); PHE Antibiotic Guidelines; UK Allergy Guidelines (Penicillin Cross-Reactivity); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Calculators
Pathways