Flucloxacillin

How it works

It binds penicillin-binding proteins to inhibit bacterial cell wall peptidoglycan cross-linking and resists staphylococcal penicillinase, giving it activity against methicillin-susceptible Staphylococcus aureus.

Prescribing in practice

• Flucloxacillin carries an MHRA-highlighted risk of cholestatic hepatitis and jaundice, which can occur up to two months after stopping and is more likely with prolonged courses and in older patients.
• It is contraindicated in patients with a history of flucloxacillin-associated jaundice or hepatic dysfunction and in those with penicillin hypersensitivity.
• Oral absorption is reduced by food, so doses are best taken on an empty stomach before meals.

Monitoring

Monitor liver function, particularly during prolonged or high-dose intravenous therapy and in older patients, and watch for signs of jaundice.

Counselling the patient

• Take it before food, spaced through the day, and complete the full course.
• Seek medical advice if you notice yellowing of the skin or eyes, dark urine or pale stools.
• Tell the team about any previous penicillin allergy or past reaction to this medicine.

Evidence & guidelines

MHRA Drug Safety advice highlights the risk of cholestatic jaundice and hepatitis with flucloxacillin, especially with courses exceeding two weeks and in the elderly.