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First-Generation Cephalosporin (Surgical Prophylaxis) Pregnancy: Generally considered safe — used in obstetric surgery; consult specialist

Cefazolin

Brand names: Kefzol

Adult dose

Dose: 1–2 g IV at induction; repeat every 3–4 hours for prolonged surgery or major blood loss >1.5 L
Route: IV slow bolus or infusion
Frequency: Single dose at induction; repeat every 3–4 hours if surgery ongoing
Max: 6 g/day
Give within 60 minutes before incision (30 minutes for IV); obesity: 3 g if >120 kg; adjust repeat doses in renal impairment

Paediatric dose

Dose: 25–30 mg/kg
Route: IV
Frequency: Single pre-operative dose
Max: 2 g/dose
Neonates: 25 mg/kg at induction

Dose adjustments

Renal

Reduce dose if eGFR <35 mL/min; extend interval in severe renal impairment

Hepatic

No adjustment required

Paediatric weight-based calculator

Neonates: 25 mg/kg at induction

Clinical pearls

  • Gold standard for orthopaedic surgical prophylaxis: SIGN 104 and NICE NG125 recommend cefazolin as first-line for clean and clean-contaminated procedures including arthroplasty, ORIF, and spinal surgery; superior gram-positive coverage with adequate gram-negative activity
  • Timing critical: administer within 60 minutes of incision (at anaesthetic induction); Classen et al. NEJM 1992 landmark study demonstrated that antibiotic administration within 2 hours of incision reduced SSI rate; late administration significantly increases infection risk
  • MRSA colonisation: if patient is MRSA-positive or recent MRSA contact, switch to teicoplanin or vancomycin for prophylaxis — cefazolin has no MRSA activity; preoperative MRSA screening recommended for elective arthroplasty in high-risk centres
  • Re-dosing rules: every 3–4 hours during prolonged surgery and after major blood loss >1.5 L — prevents tissue level dropping below MIC; no benefit to extending prophylaxis beyond wound closure (SIGN 104)
  • Cross-reactivity with penicillin: historical 10% figure is outdated — true cross-reactivity <1–2%; documented mild penicillin rash is NOT a contraindication to cefazolin; only avoid in documented anaphylaxis or urticaria to penicillin

Contraindications

  • Cephalosporin allergy
  • Severe penicillin allergy with documented cross-reactivity

Side effects

  • Injection site reaction
  • Rash
  • Diarrhoea
  • Elevated LFTs
  • Eosinophilia
  • Positive Coombs test

Interactions

  • Aminoglycosides — potential additive nephrotoxicity
  • Probenecid — increased cefazolin levels
  • Warfarin — minor INR effect

Monitoring

  • Wound for SSI signs post-operatively
  • Allergy status before administration
  • Renal function if repeat dosing

Reference: BNFc; BNF 90; SIGN 104 (Antibiotic Prophylaxis in Surgery); NICE NG125; Classen et al. NEJM 1992; SPC Kefzol. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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