ClinCalc Pro
Menu
Calculators Drugs Pathways AI Dx Donate Get the App
Antibiotic — Penicillinase-Resistant Penicillin Pregnancy: Safe — widely used in pregnancy

Flucloxacillin (Burns — Wound Infection)

Brand names: Floxapen

Adult dose

Dose: 500 mg–1 g four times daily
Route: Oral / IV
Frequency: Four times daily
Max: 2 g IV every 6 hours (severe infection)
First-line for MSSA burns wound infection (early infection, days 1–5). Take oral doses on empty stomach (30 min before food). IV for severe infection or failed oral. Cover for S. aureus — most common early burns pathogen.

Paediatric dose

Dose: 12.5–25 mg/kg
Route: Oral / IV
Frequency: Four times daily
Max: 1 g/dose (IV)
12.5–25 mg/kg/dose four times daily. Neonates: 25 mg/kg twice daily IV under specialist guidance.

Dose adjustments

Renal

No dose adjustment required in mild–moderate renal impairment.

Hepatic

Caution — rare cholestatic hepatitis with flucloxacillin (MHRA warning); avoid if history of flucloxacillin-associated jaundice.

Paediatric weight-based calculator

12.5–25 mg/kg/dose four times daily. Neonates: 25 mg/kg twice daily IV under specialist guidance.

Clinical pearls

  • MHRA safety: flucloxacillin-associated cholestatic jaundice — usually occurs weeks to months after treatment; elderly more at risk. Review and stop if jaundice develops.
  • NOT active against MRSA — if MRSA suspected or confirmed, switch to vancomycin or teicoplanin
  • Early burns wound infection (days 1–5): usually Gram-positive — flucloxacillin appropriate empirically pending swab results

Contraindications

  • Penicillin allergy
  • Previous flucloxacillin-associated cholestatic jaundice

Side effects

  • GI upset (oral)
  • Cholestatic hepatitis (rare — MHRA warning, especially with courses >2 weeks or age >55)
  • Anaphylaxis
  • Neutropenia (prolonged high dose)

Interactions

  • Warfarin (prolonged courses increase INR)
  • Methotrexate (reduced renal excretion)

Monitoring

  • LFTs for courses >2 weeks
  • Wound swab culture and sensitivities
  • Clinical response at 48–72 hours

Reference: BNFc; BNF 90; MHRA Drug Safety Update (Flucloxacillin Hepatotoxicity); BBA Burns Infection Guidelines; BNFc. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

Calculators