First-Generation Cephalosporin (Surgical Prophylaxis) Pregnancy: Pregnancy Category B (US labelling). Animal reproduction studies revealed no evidence of impaired fertility or harm to the fetus; no adequate and well-controlled studies in pregnant women. Should be used during pregnancy only if clearly needed.

Cefazolin

Brand names: Kefzol

This entry covers cefazolin used as intravenous surgical antibiotic prophylaxis in orthopaedic and trauma surgery, including arthroplasty and fracture fixation; it is a first-generation cephalosporin.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Moderate to severe infections: 500 mg to 1 gram every 6 to 8 hours

Route: Intravenous or intramuscular

Frequency: Every 6 to 8 hours

Max: In rare instances, doses of up to 12 grams per day have been used

Mild infections caused by susceptible gram-positive cocci: 250 mg to 500 mg every 8 hours. Acute uncomplicated urinary tract infections: 1 gram every 12 hours. Pneumococcal pneumonia: 500 mg every 12 hours. Severe, life-threatening infections (e.g. endocarditis, septicaemia): 1 gram to 1.5 grams every 6 hours. Perioperative prophylaxis: 1 gram IV or IM 1/2 hour to 1 hour prior to start of surgery; for lengthy procedures (2 hours or more) 500 mg to 1 gram IV or IM during surgery; then 500 mg to 1 gram IV or IM every 6 to 8 hours for 24 hours postoperatively. In surgery where infection may be particularly devastating (e.g. open-heart surgery and prosthetic arthroplasty), prophylactic administration may be continued for 3 to 5 days following completion of surgery.

Paediatric dose

Route: Intravenous or intramuscular

Frequency: Divided into 3 or 4 equal doses

Max: Total daily dosage may be increased to 100 mg/kg for severe infections

In pediatric patients older than 1 month, a total daily dosage of 25 to 50 mg/kg of body weight divided into 3 or 4 equal doses is effective for most mild to moderately severe infections. Total daily dosage may be increased to 100 mg/kg for severe infections. Safety for use in premature infants and neonates has not been established; use in these patients is not recommended. Source: US labelling (openFDA) — verify against UK SPC.

Dose adjustments

Renal

Adults (after an initial loading dose appropriate to severity): creatinine clearance 55 mL/min or greater (or serum creatinine 1.5 mg% or less) — full doses; CrCl 35 to 54 mL/min — full doses but restricted to at least 8-hour intervals; CrCl 11 to 34 mL/min — 1/2 the usual dose every 12 hours; CrCl 10 mL/min or less — 1/2 the usual dose every 18 to 24 hours.

Dose auto-extracted from US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Known allergy to the cephalosporin group of antibiotics

Side effects

Diarrhoea, nausea, vomiting, anorexia, stomach cramps, oral candidiasis, pseudomembranous colitis (gastrointestinal)
Anaphylaxis, eosinophilia, itching, drug fever, skin rash, Stevens-Johnson syndrome (allergic)
Neutropenia, leukopenia, thrombocytopenia, thrombocythemia (haematologic)
Transient rise in SGOT, SGPT and alkaline phosphatase; hepatitis (hepatic)
Phlebitis at injection site; pain at IM injection site (local reactions)

Interactions

Probenecid — may decrease renal tubular secretion of cephalosporins, resulting in increased and more prolonged cephalosporin blood levels

Clinical monograph

How it works

Cefazolin binds penicillin-binding proteins to inhibit bacterial cell-wall peptidoglycan synthesis, giving bactericidal activity against common skin staphylococci and streptococci responsible for surgical-site infection.

Prescribing in practice

Give within the recommended window before skin incision to achieve adequate tissue concentrations at the time of surgery, with redosing for prolonged procedures or major blood loss per protocol.
Avoid in patients with a history of severe immediate hypersensitivity to penicillins or cephalosporins, and consider an alternative where MRSA cover is required.
Adjust dosing in significant renal impairment, as cefazolin is renally cleared.

Monitoring

Monitor for hypersensitivity reactions around administration and review renal function where repeated or prolonged dosing is needed.

Counselling the patient

This antibiotic is given at the time of your operation to lower the risk of wound infection.
Tell the team about any previous reaction to penicillins or cephalosporins before it is given.

Evidence & guidelines

First-generation cephalosporins such as cefazolin are recommended as standard surgical antibiotic prophylaxis in orthopaedic surgery by SIGN and other guidance.

Reference: SIGN 104 (Antibiotic Prophylaxis in Surgery); NICE NG125; Classen et al. NEJM 1992; SPC Kefzol; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways