Flucloxacillin

What is flucloxacillin?

Flucloxacillin is a penicillin-type antibiotic used to treat bacterial infections. It’s a narrow-spectrum antibiotic primarily effective against penicillinase-producing staphylococci (e.g., Staphylococcus aureus)[1]. 

How does flucloxacillin work?

It works by inhibiting the formation of bacterial cell walls, leading to the destruction of the bacteria[1]. 

What is flucloxacillin used to treat?

Flucloxacillin is commonly prescribed for[1]: 

• Skin and soft tissue infections (e.g. cellulitis, impetigo) 

• Wound infections 

• Bone infections (osteomyelitis) 

• Ear infections 

• Chest infections 

• Throat or nose infections 

• Heart infections (endocarditis) 

• Blood infections (sepsis) 

• Urinary tract infections 

• Preventing infections during major surgery, especially heart or orthopedic procedures, typically administered as an intravenous dose in hospital settings[2]  

How do you take flucloxacillin?

Flucloxacillin is only available on prescription and comes in capsules, liquid form, or as an injection (usually in hospital settings). It should be taken on an empty stomach, at least 30 to 60 minutes before or 2 hours after food. The capsules should be swallowed whole with water. Doses should be spaced evenly: e.g. morning, midday, late afternoon, and bedtime[1]. 

A liquid form is available for children or those who struggle with capsules. If you take the liquid form, it should come with a syringe or spoon designed to hold the correct amount. If you do not have either, do not use a kitchen teaspoon as you may administer the wrong dose. Shake the bottle well before using[1]. 

Who can take flucloxacillin?

Flucloxacillin is generally safe for adults and children, including pregnant and breastfeeding women[1]. 

It may not be suitable for: 

• People who have ever had a reaction to flucloxacillin 

• Patients with a history of hypersensitivity to penicillin or cephalosporins due to the risk of cross-reactivity 

• Have had liver problems (e.g. jaundice) after taking flucloxacillin 

• Have severe kidney or liver disease (dose adjustments may be needed) 

Please tell your doctor or pharmacist about any conditions you may have before starting flucloxacillin, and always follow the instructions in the Patient Information Leaflet[2]. 

What is the typical dosage of flucloxacillin?

The usual dose is between 250 mg to 500 mg, four times a day. Children’s doses can vary by age and weight[1]. 

You should always carry on taking your prescribed course of flucloxacillin treatment until it’s completed, even if you feel better. Otherwise, stopping early can contribute to antibiotic resistance and the infection returning. 

What do you do if you forget to take flucloxacillin?

 If you miss a dose, take it as soon as you remember. If it's almost time for your next dose, skip the missed dose and continue with your regular schedule. Never take 2 doses at the same time. You should contact your pharmacist or doctor if you miss multiple doses, as this may affect treatment efficacy[1]. 

What to do if you take too much flucloxacillin?

Taking one extra dose of flucloxacillin shouldn’t harm you, but if you’re concerned or have taken more than one extra dose, you should speak to a pharmacist or doctor or call 111. For severe symptoms (e.g., seizures or breathing difficulty), call 999 or visit A&E immediately[1][2].  

What are the side effects of flucloxacillin?

The most common side effects of flucloxacillin are[1]: 

• Nausea 

• Diarrhoea 

Serious but rare side effects include[1]: 

• Diarrhoea containing blood or mucus, or severe diarrhea that lasts longer than 4 days  

• Pale poo and/or dark pee, with yellowing of skin or eyes, as signs of liver problems 

• Severe skin reactions 

In very rare cases, flucloxacillin can cause a serious allergic reaction, known as anaphylaxis (rash, swelling, difficulty breathing). If you experience any of these side effects, stop taking flucloxacillin and consult your GP or call 111. For more serious side effects, call 999 immediately. 

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice.

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Medicines you can and can’t take with flucloxacillin

You should tell your doctor or pharmacist about all the medications, supplements, or herbal remedies you are taking. Especially: 

• Methotrexate 

• Probenecid (used to treat gout)  

• Warfarin (to prevent blood clots) - flucloxacillin may reduce warfarin’s effectiveness, requiring closer monitoring of INR levels 

• Other antibiotics 

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2]. 

Frequently asked questions about flucloxacillin

Can I drink alcohol while taking flucloxacillin? 

Yes, you can drink alcohol while taking flucloxacillin[1]. 

Can I take flucloxacillin during pregnancy or breastfeeding? 

Yes, Flucloxacillin is considered safe in pregnancy and breastfeeding[1]. 

Does flucloxacillin affect contraception? 

Flucloxacillin does not affect the combined and progestogen-only pills feom working. However, if you are sick or have severe diarrhoea for more than 24 hours you may not be protected so you should take extra precautions (e.g., condoms). You will need to check your pill information leaflet or get advice[2]. 

How long does flucloxacillin take to work? 

You should start feeling better within a few days. But it is very important to complete the course to stop any infection returning even if you are feeling better[1][2].

For the official NHS guide to flucloxacillin, visit their website.