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Flucloxacillin + ampicillin

Co-fluampicil

Brand names: Magnapen

Co-fluampicil is a fixed combination of flucloxacillin and ampicillin, providing penicillinase-stable cover for staphylococci together with broader activity against streptococci and some Gram-negative organisms.

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

Both components are beta-lactams that inhibit bacterial cell-wall peptidoglycan synthesis, with flucloxacillin resisting staphylococcal penicillinase.

Prescribing in practice

  • The flucloxacillin component carries an MHRA-recognised risk of cholestatic jaundice and hepatitis that can occur up to two months after stopping, more commonly with prolonged courses or in older patients.
  • Contraindicated in penicillin allergy and in anyone with previous flucloxacillin-associated jaundice or hepatic dysfunction.
  • Best taken on an empty stomach as food reduces absorption of both penicillins.

Monitoring

Monitor for jaundice or hepatic symptoms during and after treatment, particularly with longer courses.

Counselling the patient

  • Take the doses before food, spaced through the day.
  • Report yellowing of the skin or eyes, dark urine or pale stools, even after the course has finished.
  • Complete the full course and report any rash or breathing difficulty.

Evidence & guidelines

MHRA advice on flucloxacillin hepatotoxicity informs the cautions for this combination.

Reference: 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.

Pathways