Flucloxacillin (Paediatric)

How it works

It inhibits bacterial cell wall synthesis by binding penicillin-binding proteins and is stable to staphylococcal beta-lactamase, retaining activity against most Staphylococcus aureus.

Prescribing in practice

• It is contraindicated in penicillin allergy, and rare cholestatic hepatitis and jaundice can occur up to weeks after stopping, even after a short course.
• Take oral doses on an empty stomach, ideally before food, as food reduces absorption; high parenteral doses require attention to renal function and electrolytes.
• Dose by body weight using a children's formulary, with higher doses for deep-seated infections such as osteomyelitis.

Monitoring

On prolonged or high-dose courses monitor liver and renal function and observe for signs of hypersensitivity.

Counselling the patient

• Give doses about an hour before food and complete the full course.
• Report any jaundice, pale stools, dark urine, rash or itching, which can appear after treatment ends.
• Tell the team about any previous reaction to penicillin or other antibiotics.

Evidence & guidelines

Flucloxacillin is the established first-line antistaphylococcal penicillin in UK practice, with MHRA advice highlighting the risk of delayed cholestatic hepatic reactions.