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Flucloxacillin for infection

Make sure you tell your doctor if you are allergic to penicillin. Flucloxacillin is a type of penicillin - do not take it if you are allergic to penicillin.

Flucloxacillin should be taken when your stomach is empty. This means you should take your doses an hour before meals or two hours after a meal.

Space your doses out evenly over the day and complete the full course of antibiotic.

If you have an allergic reaction (such as any swelling around your mouth, any difficulties breathing or a red rash) contact a doctor straightaway.

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About flucloxacillin

Type of medicine

Penicillin antibiotic

Used for

Bacterial infections (adults and children)

Also called

Floxacillin (in US)

Available as

Capsules, oral liquid medicine and injections

Flucloxacillin is used to treat bacterial infections such as ear infections, skin infections, bone infections, and heart and chest infections. It works by killing the bacteria causing the infection.

Flucloxacillin is also used before some surgical operations to prevent an infection from developing. Flucloxacillin is available in combination with another antibiotic in a medicine called co-fluampicil. For information on this medicine read our leaflet Co-fluampicil for infection.

Before taking flucloxacillin

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking flucloxacillin it is important that your doctor or pharmacist knows:

  • If you are pregnant or breastfeeding. (Although flucloxacillin is not known to be harmful to babies, it is still important that you tell your doctor if you are expecting or breastfeeding a baby.)

  • If you have problems with the way your liver works.

  • If you have kidney problems.

  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.

  • If you have an allergic condition, or if you have ever had an allergic reaction to a medicine. This is particularly important if you have ever had a bad reaction to any penicillin antibiotic.

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How to take flucloxacillin

  • Before you start this antibiotic, read the manufacturer's printed information leaflet from inside the pack. The leaflet will give you more information about flucloxacillin and a full list of side-effects which you may experience from taking it.

  • Take your dose of flucloxacillin exactly as your doctor tells you to. It is taken four times a day Your doctor or pharmacist will tell you how many capsules (or how much liquid medicine) to take for each dose, and this information will be printed on the label of the pack to remind you. If you have been given liquid medicine for a child, read the directions carefully to make sure you measure out the correct amount of medicine.

  • You should take flucloxacillin 'on an empty stomach', which means you should take it about an hour before a meal, for example midday before lunch or in the morning before breakfast, or wait until two hours afterwards. This is because your body absorbs less flucloxacillin after a meal, which means the medicine is less effective. Space the doses out evenly during the day.

  • Swallow the capsules whole - do not chew or open them. Some people find it helps to swallow the capsules with a drink of water.

  • If you forget to take a dose, take one as soon as you remember. Try to take the correct number of doses each day, but do not take two doses at the same time to make up.

  • Even if you feel your infection has cleared up, keep taking the antibiotic until the course is finished, unless you are told to stop. This is to prevent the infection from coming back. Your doctor will tell you how long your course of treatment will last. If you still feel unwell after finishing the course, go back to see your doctor.

Getting the most from your treatment

  • Some people develop thrush (redness and itching in the mouth or vagina) after taking a course of antibiotics. If you think you have thrush speak with your doctor or pharmacist for advice.

  • If you are using oral combined hormonal contraception (the 'pill'), additional contraceptive precautions such as condoms are recommended for a time if you have sickness (vomiting) or diarrhoea which lasts for more than 24 hours. If you need further advice about this, speak with your doctor or pharmacist.

  • If you need pain relief whilst taking flucloxacillin it is best to speak to your doctor or a pharmacist first. The painkiller paracetamol is not always recommended during treatment with flucloxacillin, especially if you also have problems with the way your kidneys work.

  • If you are having an operation or any other medical treatment, tell the person carrying out the treatment that you are taking an antibiotic.

  • Flucloxacillin may stop the oral typhoid vaccine from working. If you are having any vaccinations, make sure the person treating you knows that you are taking this antibiotic.

  • If you are taking flucloxacillin over an extended period of time, your doctor will want to routinely check on your progress. Try to keep any regular appointments you have booked with your doctor, as you will need to have some blood tests to check that your liver and kidneys are working well.

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Can flucloxacillin cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with flucloxacillin. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.


flucloxacillin side-effects -

these affect fewer than 1 in 10 people

What can I do if I experience this?

Feeling sick (nausea) or being sick (vomiting)

Stick to simple foods


Drink plenty of water to replace any lost fluids. If the diarrhoea continues, becomes severe, or contains blood, let your doctor know


Skin rash

Let your doctor know as soon as possible, as your treatment may need to be changed

Important: if you develop an itchy rash, or a swollen face or mouth, or have difficulty breathing, these may be signs that you are allergic to a penicillin antibiotic. Do not take any more flucloxacillin and speak with your doctor or go to your local accident and emergency department straightaway.

If you experience any other symptoms which you think may be due to the medicine, speak with your doctor, pharmacist or health professional.

How to store flucloxacillin

  • Keep all medicines out of the reach and sight of children.

  • Store flucloxacillin capsules in a cool, dry place, away from direct heat and light.

  • If you have been given liquid medicine, store it in a refrigerator. It will have been made up by the pharmacy and lasts for seven days, so check the expiry date on the bottle and do not use it after this date.

Important information about all medicines

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

If you buy any medicines, check with a pharmacist that they are safe to take with your other medicines.

If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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