Flucloxacillin: What is it? Who Can Take It? Administration, Side Effects, Interactions and Frequently Asked Questions

It is used to treat skin infections and wounds, chest infections, such as pneumonia and bone infections.

Flucloxacillin is an antibiotic. It is used in children, often to treat ear infections and chest infections.

The medication is available by prescription only. It comes in the form of capsules or as a liquid to drink. It can also be given by injection, but this is usually done in the hospital.

Key facts

  • For most infections, patients who use the medication should feel better in a few days.
  • The most common side effects are nausea and diarrhea.
  • You can drink alcohol while taking flucloxacillin.

Who can and can not take flucloxacillin

Flucloxacillin can be taken by adults, including pregnant and lactating women.

It can also be taken by children.

To make sure flucloxacillin is safe for you, tell your doctor if:

  • You have had an allergic reaction to penicillin, flucloxacillin, or any other medication in the past.
  • Have liver or kidney problems.
  • Has had, or is about to have any vaccine.


The usual dose of flucloxacillin is 250 mg to 500 mg taken 4 times a day. In children, the dose may be lower.

It is best to take flucloxacillin on an empty stomach. This means 30 to 60 minutes before a meal or snack, or at least 2 hours later.

Try to space your doses evenly throughout the day. For example, first thing in the morning (before breakfast), around noon (before lunch), in the late afternoon (before tea) and before bedtime.

Keep taking this medication until you have completed the treatment, even if you feel better. If you stop your treatment early, your problem may come back.

How to take it

Swallow the entire flucloxacillin capsules with a drink of water. Do not chew them or break them.

There is a liquid flucloxacillin available for children and people who find it difficult to swallow tablets.

If you or your child is taking flucloxacillin as a liquid, your pharmacist will usually compensate you. The medication will come with a syringe or spoon to help you take the correct amount. If you do not have a syringe or spoon, ask your pharmacist for one.

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 that cause the infection.

Flucloxacillin is also used before some surgical operations to prevent the development of an infection.

Before taking flucloxacillin

Before you start taking flucloxacillin, it is important that your doctor or pharmacist knows:

  • If you are pregnant or breast-feeding (Although flucloxacillin is not known to be harmful to babies, it is still important to tell your doctor if you are expecting or breast-feeding a baby).
  • If you have problems with the way your liver works.

Take 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 amount of liquid medicine) to take for each dose, and this information will be printed on the package label to remind you.

You should take flucloxacillin on an empty stomach, which means you should take it about an hour before your meal or wait until two hours later.

This is because your body absorbs less flucloxacillin after a meal, which means that the medication is less effective. Distribute the doses evenly throughout the day.

If you forget to take a dose, take it as soon as you remember. Try to take the right amount of dose each day, but do not take two doses at the same time to compensate.

Some people develop canker sores (redness and itching in the mouth or vagina) after taking antibiotic treatment. If you think you have thrush, talk to your doctor or pharmacist for advice.

If you are using hormonal contraceptives in oral combinations, additional contraceptive precautions, such as condoms, are recommended since diarrhea and vomiting occasionally occur. If you need more information, talk to your doctor or pharmacist.

If you are going to have an operation or any other medical treatment, tell the person doing the treatment that you are taking an antibiotic.

Flucloxacillin may prevent the oral typhoid vaccine from working. If you have any vaccinations, make sure the person who treats you knows that you are taking this antibiotic.

If you are taking flucloxacillin for a long period of time, your doctor will want to routinely monitor your progress. Try to keep your regular appointments that you have booked with your doctor, since you will have to do some blood tests to verify that your liver and kidneys are working well.

What happens if I take too much?

  • Try to take the right amount of dose each day, leaving at least 3 hours between doses.
  • Taking an extra dose of flucloxacillin by accident is unlikely to hurt you or your child.
  • Talk to your pharmacist or doctor if you are worried or if you take more than 1 additional dose.

Side effects

Like all medications, flucloxacillin may cause side effects in some people, although not everyone will receive them.

Common side effects

These common side effects of flucloxacillin occur in more than 1 in 100 people. Keep taking the medication, but tell your doctor or pharmacist if these side effects bother you or do not go away:

  • Feeling sick.
  • Vomiting
  • Diarrhea.
  • Swelling and indigestion.

Serious side effects

Serious side effects are rare and occur in less than 1 in 1,000 people.

Tell a doctor immediately if you get:

  • Severe and bloody diarrhea.
  • Yellowing of the eyes and skin; This can be a sign of liver problems.
  • A severe skin rash, which includes flushing, fever, blisters or ulcers, round red spots, or skin that looks like it burned.
  • Bruising or discoloration of the skin.
  • Pain in the joints or muscles that appears after 2 days of taking the medication.
  • Dark urine.

Some of these serious side effects may not occur for up to 2 months after the end of the flucloxacillin cycle.

Serious allergic reaction

In rare cases, it is possible to have a severe allergic reaction to flucloxacillin.

A severe allergic reaction is cause for an emergency. In these cases the most advisable thing is to have contact with your doctor immediately due to the consequences that it implies if you or someone around you is having a severe allergic reaction.

The warning signs of a severe allergic reaction are:

  • Contract a skin rash that may include itching, redness, swelling, blistering or peeling skin.
  • Wheezing
  • Oppression in the chest or throat.
  • Have trouble breathing or talking.
  • Swelling of the mouth, face, lips, tongue or throat.

These are not all the side effects of flucloxacillin.

How to deal with side effects

What to do with:

Feeling bad: stick to simple foods and try not to eat rich or spicy foods.

Diarrhea and vomiting: Drink plenty of water or other fluids. It can also help to take oral rehydration solutions that you can buy at a pharmacy to prevent dehydration. Do not take other medications to treat diarrhea or vomiting without talking to a pharmacist or doctor.

Pregnancy and lactation

It is generally safe to take flucloxacillin during pregnancy and during breastfeeding.

You must inform your specialist doctor if you are pregnant, or if in any case you make attempts to get pregnant. Another aspect to consider is breastfeeding if you have a small child.


There are some medications that do not mix well with flucloxacillin.

Tell your doctor if you are taking these medicines before you start with flucloxacillin:

You should also tell your doctor if you have recently received or are about to get a vaccination.

Blend of flucloxacillin with herbal remedies and supplements

There are no known problems with the taking of herbal remedies and supplements with flucloxacillin.

However, for safety, tell your doctor or pharmacist if you are taking other medicines, including herbal remedies, vitamins or supplements.

Common questions

How does flucloxacillin work?

Flucloxacillin is one of a group of antibiotics called penicillins. It works by damaging the cell walls of bacteria and killing them.

When will I feel better?

For most infections, you should feel better in a few days.

It is very important to continue taking flucloxacillin until the treatment is finished. Do this even if you feel better. It will help stop the infection.

What happens if I do not improve?

Tell your doctor if you do not start to feel better after taking flucloxacillin for 3 days. Also tell them if, at any time, you start to feel worse.

Are there serious consequences when taking it?

Some people get a fungal infection called thrush after taking a treatment with antibiotics such as flucloxacillin. It happens because antibiotics kill the normal harmless bacteria that help protect against canker sores.

Consult your doctor or pharmacist if this happens.

Will my contraceptive pill stop working?

Flucloxacillin does not stop the functioning of contraceptive pills.

However, if flucloxacillin makes you vomit or have severe diarrhea (6 to 8 watery potions in 24 hours) for more than 24 hours, your contraceptive pills may not protect you from pregnancy. Look in the pack of pills to find out what to do.

Will it reduce my fertility?

Flucloxacillin will not reduce fertility for men and women.

I can drive?

Yes, flucloxacillin should not affect the fact that you can drive.

Can I drink alcohol during treatment?

Yes, you can drink alcohol while taking flucloxacillin.

Is there any food or drink I should avoid?

You do not need to avoid any food or drink while you are taking flucloxacillin. However, be sure to take it on an empty stomach.