Amoxicillin + clavulanic acid

Also called co-amoxiclav

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

Type of medicine Also called
  • Antibiotic (to treat infections)
  • Penicillin antibiotic
  • Augmentin ®
  • Synermox®
  • Curam®
  • m-Amoxiclav®

What is amoxicillin clavulanic acid?

Amoxicillin clavulanic acid is an antibiotic used to treat different infections caused by bacteria such as sinus infections, urine infections, skin infections, joint infections and some dental infections. It works by killing or stopping the growth of bacteria (bugs) and gets rid of the infection. Amoxicillin clavulanic acid is not effective against infections caused by viruses. It belongs to a group of antibiotics called penicillins. In New Zealand amoxicillin clavulanic acid is available as tablets and liquid and in the hospital as an injection.


  • The usual dose of amoxicillin clavulanic acid in adults is 625 milligrams 3 times daily.
  • The dose for children will depend on their body weight. 
  • Your doctor will advise you how long to take amoxicillin clavulanic acid for (usually 3 to 10 days).
  • Always take your medicine 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 amoxicillin clavulanic acid

  • Tablet: swallow the tablet with a glass of water. 
  • Liquid: shake the medicine well. Measure the right amount using an oral syringe or medicine spoon. You can get these from your pharmacy. Do not use a kitchen spoon as it will not give you the right amount. Read more: Tips on how to give medicines to babies and children.
  • Take amoxicillin clavulanic with or after food. This helps to prevent stomach upset.
  • Amoxicillin clavulanic acid is usually given three times a day. Try to space the doses evenly throughout the day such as the first thing in the morning, early afternoon and at bedtime, or at mealtimes. 
  • If you forget to take your dose, take it as soon as you remember that day. But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.
  • It is important to take the whole course of antibiotics for the number of days your doctor has told you to. Do not stop taking it, even if you feel your infection has cleared up. 

Precautions - before starting amoxicillin clavulanic acid

  • Do you have glandular fever?
  • Have ever had an allergic reaction to a medicine, especially a penicillin antibiotic?
  • Are you pregnant or breast-feeding?
  • Do you have problems with the way your liver or kidneys work?
  • Are taking any other medicines? This includes any medicines you are taking which you can buy without a prescription, as well as herbal and complementary medicines?

If so, it’s important that you tell your doctor or pharmacist before you start amoxicillin clavulanic acid. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

Precautions - while taking amoxicillin clavulanic acid

  • Store your amoxicillin clavulanic acid tablets in a cool, dry place, away from direct heat and light.
  • If you have been given liquid medicine, this will have been made up by the pharmacy and you may need to keep it in the fridge - check the instructions on the bottle. Make sure the medicine does not freeze.
  • If your child is sick (vomits) and it is less than 30 minutes after having a dose, give them the same dose again. But, if your child is sick (vomits) and it is more than 30 minutes after having a dose, you do not need to give them another dose. Wait until the next normal dose.
  • If you are taking the contraceptive 'pill', the effectiveness of the 'pill' can be reduced if you have a bout of being sick (vomiting) or diarrhoea which lasts for more than 24 hours. If this happens, ask your doctor or pharmacist for advice about what contraception to use over the following few days. 

Possible side effects

Like all medicines, amoxicillin clavulanic acid 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?
  • Nausea (feeling sick) or vomiting
  • Take amoxicillin clavulanic acid soon after a meal.
  • Let your doctor or pharmacist know if you are also taking the oral contraceptive pill and have been vomiting
  • Diarrhoea (loose, watery stools)
  • This is quite common with amoxicillin clavulanic acid
  • It should settle after a few days
  • Tell your doctor if it becomes severe or contains blood 
  • If you have diarrhoea and are also taking the oral contraceptive pill, let your doctor or pharmacist know.
  • 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 amoxicillin clavulanic acid.
  • Tell your doctor immediately or ring HealthLine.


Amoxicillin clavulanic acid may interact with a few medications and herbal supplements, so check with your doctor or pharmacist before starting amoxicillin clavulanic acid.

Learn more

The following links have more information about amoxicillin clavulanic acid.

Medsafe Consumer Information Sheet: Augmentin    

New Zealand Formulary Patient Information: amoxicillin and clavulanic acid


  1. Amoxicillin + clavulanic acid New Zealand Formulary
  2. Antibiotics: choices for common infections BPAC, 2017
Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 26 Jun 2018