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Antibiotic (Penicillinase-Resistant Penicillin)

Flucloxacillin

Brand names: Floxapen

Flucloxacillin is a narrow-spectrum, penicillinase-stable penicillin used mainly for staphylococcal and streptococcal skin/soft-tissue and other infections.

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 stable to staphylococcal beta-lactamase, inhibiting bacterial cell-wall synthesis.

Prescribing in practice

  • It can cause cholestatic hepatitis/jaundice that may appear up to several weeks after stopping, and is commoner in older patients and with longer courses.
  • Absorption is reduced by food — take it before meals.
  • Avoid in penicillin allergy.

Monitoring

Consider liver function with prolonged courses; review for jaundice even after the course.

Counselling the patient

  • Take it on an empty stomach, about an hour before food.
  • Report yellowing of the skin/eyes or dark urine — even after finishing the course.
  • Complete the course.

Evidence & guidelines

First-line for many staphylococcal/streptococcal soft-tissue infections (NICE/local guidance).

Reference: NICE CKS Cellulitis; PHE Antibiotic Guidelines; 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.

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