Patient leaflet - Flucloxacillin 500 mg capsules
1. What your medicine is and what it is used for
Flucloxacillin is an antibiotic used to treat infections by killing the bacteria that can cause them. It belongs to a group of antibiotics called “penicillins”.
Flucloxacillin is used to treat:
- chest infections - throat or nose infections
- ear infections - skin and soft tissue infections
- heart infections - bone and joint infections
- meningitis - digestive system infections
- blood infections
- kidney, bladder or urethra (the tube which carries urine from the bladder) infections.
Flucloxacillin can also be used to prevent infections during major surgery, particularly heart or orthopaedic surgery.
2. What you need to know before you take your medicine
Do not take this medicine if:
- You are allergic to flucloxacillin or any other penicillin antibiotics (see symptoms in section 4).
- You are allergic to any of the other ingredients of this medicine (listed in section 6).
- You have suffered previously from liver problems (e.g. jaundice) after taking flucloxacillin.
- You have had an allergic reaction to β-lactam antibiotics (e.g. penicillins, cephalosporins).
Warnings and precautions
Talk to your doctor or pharmacist before taking this medicine if:
- You suffer from kidney problems, as you may require a lower dose than normal (convulsions may occur very rarely in patients with kidney problems who take high doses)
- You suffer from liver problems, as this medicine could cause them to worsen
- You are 50 years of age or older
- You have other serious illnesses (apart from the infection this medicine is treating)
- You are taking this medicine for a long time as regular tests of liver and kidney function are advised
- You are on a sodium-restricted diet.
You are taking or will be taking paracetamol
There is a risk of blood and fluid abnormality (high anion gap metabolic acidosis) which occurs when there is an increase in plasma acidity, when flucloxacillin is used concomitantly with paracetamol, particularly in certain groups of patients at risk, e.g. patients with severe renal impairment, sepsis or malnutrition, especially if the maximum daily doses of paracetamol are used. High anion gap metabolic acidosis is a serious disease that must have urgent treatment.
The use of flucloxacillin, especially in high doses, may reduce the potassium levels in the blood (hypokalaemia). Your doctor may measure your potassium levels regularly during the therapy with higher doses of flucloxacillin.
Other medicines and Flucloxacillin Capsules
Tell your doctor or pharmacist before taking this medicine if you are taking any other medicines, especially:
- Probenecid or sulfinpyrazone (used to treat gout)
- Methotrexate (a chemotherapy drug)
- Oral typhoid vaccine (antibiotics can make this less effective)
- Sugammadex (used with general anaesthetics)
- Piperacillin (an antibiotic taken by injection)
- Warfarin (medicine to prevent blood clotting)
- Voriconazole (used against fungal infections)
Some medicines may affect the way others work. Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines. This means medicines you have bought yourself as well as medicines on prescription from a doctor.
Pregnancy and breast-feeding
If you are pregnant or breast feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine.
Tests
Regular monitoring of liver and kidney function should be performed whilst taking Flucloxacillin capsules.
Tell your doctor that you are taking Flucloxacillin if you are having urine tests or blood tests because Flucloxacillin may affect the results.
Your medicine contains sodium
This medicine contains less than 1 mmol sodium (23 mg) per capsule, that is to say essentially ‘sodium-free’.
3. How to take your medicine
Always take this medicine exactly as your doctor or pharmacist has told you. Their directions may differ from the information contained in this leaflet. The pharmacist’s label should tell you how much to take and how often. Check with your doctor or pharmacist if you are not sure.
Take this medicine when your stomach is empty. This means an hour before food or 2 hours after food. It is important that you take your medicine at the right times.
The dose will depend on the patient and will be decided by your doctor. However, the usual doses for each age group are:
Adults (including the elderly)
- The usual dose is 250mg four times a day
- Bone or heart infection: Up to 8g daily, in divided doses at six to eight hours apart.
- Surgical prophylaxis: 1 to 2g IV at induction of anaesthesia followed by 500mg every six hours for up to 72 hours.
Use in children and adolescents
Children (10-18 years of age): 250mg four times daily Children (2-10 years of age): 125mg four times daily Children under 2 years of age: 62.5mg four times daily
Patients with kidney problems
If you suffer from severe kidney failure your doctor will give you lower or fewer doses.
If you take more of your medicine than you should
If you (or someone else) swallow a lot of capsules at the same time, or you think a child may have swallowed any contact your nearest hospital casualty department or tell your doctor immediately. Symptoms of an overdose include feeling or being sick and diarrhoea.
If you forget to take your medicine
Do not take a double dose to make up for a forgotten dose. If you forget to take a dose, take it as soon as you remember, then carry on as before, try to wait about four hours before taking the next dose.
If you stop taking your medicine
Do not stop treatment early because some bacteria may survive and cause the infection to come back.If you have any further questions on the use of this medicine, ask your doctor or pharmacist.
4. Possible side effects
Like all medicines, this medicine can cause side effects, although not everybody gets them. If they occur, they are likely to be temporary, and not serious. However, some may be serious and need medical attention.
STOP taking Flucloxacillin Capsules and contact your doctor immediately if you experience:
- allergy or hypersensitivity including itchy rash, itching, sore mouth or eyes, swelling of the face, lips, throat or tongue or breathing problems
- severe, possibly bloody, diarrhoea
- jaundice (yellow colour in the skin and whites of the eyes), hepatitis (liver inflammation) - sometimes these effects on the liver can be delayed for up to 2 months after finishing treatment.
- severe skin rash with flushing, fever, blisters or ulcers (Stevens-Johnson syndrome)
severe rash with reddening, peeling and swelling of the skin that looks like a burn (toxic epidermal necrolysis).
-
changes in numbers of blood cells (causing unexplained bleeding, bruising or skin discolouration).
Tell your doctor if you notice any of the following effects:
Common (may affect up to 1 in 10 people):
- diarrhoea, stomach upset and feeling sick - should be mild and wear off after a few days.
Very rare (may affect up to 1 in 10,000 people):
- difficulty passing water or blood in the urine (may be a sign of inflammation of the kidney)
- unusual bleeding or bruising, anaemia (may be caused by changes in the numbers of blood cells)
- joint or muscle pains or fever (may develop 2 days after starting treatment)
- skin rash with circular, red patches (Erythema multiforme)
- blood and fluid abnormality (high anion gap metabolic acidosis) which occurs when there is an increase in plasma acidity, when flucloxacillin is used concomitantly with paracetamol, generally in the presence of risk factors (see section 2).
Some of these reactions can be delayed for up to two months after finishing the treatment.
Not known (frequency cannot be estimated from the available data)Serious skin reactions
A red, scaly rash with bumps under the skin and blisters (exanthematous pustulosis). Contact a doctor immediately if you get any of these symptoms.
- Low potassium levels in the blood (hypokalaemia), which can cause muscle weakness, twitching or abnormal heart rhythm.
- Pain in oesophagus (the tube that connects mouth with stomach) and other related symptoms, such as difficulties in swallowing, heartburn, throat irritation or chest pain.
Check with your doctor if you have any problems while taking this medicine, even if you think the problems are not connected with the medicine, or are not listed in this leaflet.
Reporting of side effects
If you get any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the yellow card scheme at www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.
By reporting side effects you can help provide more information on the safety of this medicine.
5. How to store your medicine
KEEP THIS MEDICINE OUT OF THE SIGHT AND REACH OF CHILDREN
Do not use this medicine after the expiry date which is stated on the label after EXP. The expiry date refers to the last day of that month.
Securitainers: Store below 25oC. Store in the original package. Keep the container tightly closed in order to protect from light and moisture.
Blister packs: Store below 25oC. Do not open the foil pouch until ready to use the product. Once opened the foil pouch may be discarded. Store the product in the outer carton in order to protect from light and moisture.
Return any left-over medicine to the pharmacist. Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help protect the environment.
6. Contents of the pack and other information
What Flucloxacillin Capsules contain
The active substance is flucloxacillin as flucloxacillin sodium.
The other ingredients are sodium starch glycolate, magnesium stearate, red iron oxide (E172), yellow iron oxide (E172), black iron oxide (E172), titanium dioxide (E171) and gelatin.
Please see further information on sodium in section 2.
What Flucloxacillin Capsules look like and contents of the pack
The 250mg capsules are opaque caramel and grey, printed with ‘FXN 250’ in black ink. The capsules contain a granular off-white powder.
The 500mg capsules are opaque caramel and grey, printed with ‘FXN 500’ in black ink. The capsules contain a granular off-white powder.
Both strengths are available in the following pack sizes:
Securitainers are available in pack sizes of 15, 18, 20, 21, 28, 30, 50, 100, 250 & 500 capsules.
Blister packs are available in pack sizes of 15, 18, 20, 21, 28, 30, 50, 100, 250 & 500 capsules. Not all pack sizes may be marketed.
Marketing Authorisation Holder and Manufacturer
Kent Pharma UK Limited, Connect 38, 1, Dover Place, Ashford, Kent, United Kingdom, TN23 1FB.
Distributed by: **
PL 51463/0240
PL 51463/0241
This leaflet was last revised in May 2026
**Kent Pharmaceuticals Limited, Repton Road, Measham, DE12 7DT, UK Actavis Barnstaple, EX32 8NS, UK