Sounds like 'flu-CLOX-i-SIL-in'

Easy-to-read medicine information about flucloxacillin – what it is, how to take flucloxacillin safely and possible side effects.

Type of medicine Also called
  • Antibiotic (to treat infections)
  • Penicillin antibiotic 
  • Staphlex®
  • Flucloxacillin (AFT)®
  • Flucloxin®

What is flucloxacillin?

  • Flucloxacillin is an antibiotic used to treat infections caused by bacteria such as skin infections.
  • It works by killing or stopping the growth of bacteria (bugs) that cause the infection.


  • The usual dose of flucloxacillin is 250 mg or 500 mg four times a day, depending on the type of infection and how severe it is. 
  • Your doctor will advise you on how long to take flucloxacillin for (usually 5 to 10 days).
  • Always take your flucloxacillin exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much to take, how often to take it, and any special instructions. 

How to take flucloxacillin

  • Swallow the capsule with a glass of water.
  • Take flucloxacillin on an empty stomach, which means, take it between meal times, one hour before eating food or two hours after food. This is because your body absorbs less flucloxacillin after a meal, making it less effective.
  • Take flucloxacillin at the same times each day. Try to space the doses evenly apart during waking hours, for example: 8am, 1pm, 5pm and 10pm. 
  • Keep taking flucloxacillin until you finish all the capsules, or for as long as your doctor or pharmacist tells you to.
  • Do not stop taking flucloxacillin, even if you feel better after a few days, unless your doctor tells you to.
  • If you forget to take flucloxacillin, take it as soon as you remember. But, if it is nearly time for your next capsule, just take the next capsule at the right time. Do not take double the amount of capsules.

Possible side effects

Like all medicines, flucloxacillin can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Side effects What should I do?
  • Diarrhoea (loose, watery stools)
  • These may go away with time.
  • Tell your doctor if troublesome.
  • Vaginal itching, soreness or discharge (thrush)
  • Tell your doctor or pharmacist.
  • Allergic reaction such as skin rash, itching, swelling of the lips, face, and mouth or difficulty breathing
  • Stop taking flucloxacillin.
  • Tell your doctor immediately or ring HealthLine.
  • Signs of problems with your liver such as yellowing of the skin or eyes, dark urine, pain in the abdomen.
  • Tell your doctor immediately or ring HealthLine.


  • Flucloxacillin may interact with a few medications and herbal supplements, so check with your doctor or pharmacist before starting flucloxacillin or before starting any new medicines.
  • If you are taking the contraceptive pill (birth control pill), it may not be as effective if you experience diarrhoea or vomiting (being sick) which lasts more than 24 hours. If this happens, speak to your doctor or pharmacist about additional contraceptive precautions.

Learn more

Medsafe Consumer Information Sheet
Flucloxacillin (AFT) 

New Zealand Formulary Patient Information: Flucloxacillin

Credits: Sandra Ponen, Pharmacist. Reviewed By: Dr J Bycroft. Health Navigator NZ