Flucloxacillin – Penicillin antibiotic for skin and soft tissue infections.
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What is Flucloxacillin?
Flucloxacillin is a penicillin antibiotic specifically designed to treat infections caused by staphylococcal bacteria, particularly those affecting the skin and soft tissues. It’s resistant to penicillinase, making it effective against bacteria that are resistant to regular penicillin.
Book an online consultation if you have signs of a skin infection such as redness, swelling, warmth, or pus. Our qualified GPs can assess your condition and prescribe appropriate antibiotic treatment when needed.
What is Flucloxacillin used for?
- Skin and soft tissue infections
- Staphylococcal infections
- Cellulitis
- Impetigo
- Infected eczema
- Wound infections
- Boils and abscesses
How does Flucloxacillin work?
A penicillinase-resistant penicillin that targets staphylococcal bacteria by disrupting their cell wall formation, particularly effective against penicillin-resistant staphylococci.
Dosage and Administration
Adults
250-500 mg four times daily, taken on an empty stomach.
Children
25-50 mg per kg daily in divided doses—GP will calculate based on weight.
Important Notes
- Take on an empty stomach (1 hour before or 2 hours after meals).
- Take at evenly spaced intervals throughout the day.
- Complete the full course even if infection appears to clear.
- Capsules should be swallowed whole with plenty of water.
Side Effects
Common Side Effects
- Nausea and vomiting
- Diarrhoea
- Abdominal pain
- Skin rash
- Bloating and wind
Serious Side Effects
Seek immediate medical attention if you experience:
- Severe allergic reactions (anaphylaxis)
- Clostridioides difficile-associated diarrhoea (CDAD)
- Severe liver reactions (cholestatic jaundice)
- Stevens-Johnson syndrome (severe skin reaction)
Important Warnings
- Do not take if you have a penicillin allergy.
- Tell your GP if you have liver problems or a history of jaundice.
- May cause false-positive results in some urine glucose tests.
- Can reduce effectiveness of oral contraceptives—use additional contraception.
Drug Interactions
Tell your GP if you're taking any of the following medications:
- Methotrexate—may increase methotrexate toxicity.
- Oral contraceptives—may reduce effectiveness.
- Probenecid—may increase flucloxacillin levels.
- Warfarin—may enhance anticoagulant effects.
Frequently Asked Questions
Why must I take Flucloxacillin on an empty stomach?
Food significantly reduces the absorption of Flucloxacillin, making it much less effective. Take it 1 hour before or 2 hours after meals for best results.
How is Flucloxacillin different from other penicillins?
Flucloxacillin is specifically designed to work against staphylococcal bacteria that are resistant to regular penicillin, making it ideal for skin infections.
Can I stop taking it when my skin infection looks better?
No, you must complete the full course. Stopping early can lead to the infection returning and may contribute to antibiotic resistance.
What should I do if I develop severe diarrhoea?
Contact your GP immediately, especially if the diarrhoea is bloody or contains mucus, as this could indicate a serious bowel infection.
Medically Reviewed by: Mohammed Hassan - Independent Prescriber
Last Updated: 2025-01-14