Sounds like 'MET-ro-NYE-da-zole'

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

Type of medicine Also called
  • Antibiotic
  • Trichozole®

What is metronidazole?

  • Metronidazole is an antibiotic that is used to treat infections caused by bugs that do not require oxygen to grow and multiply (called anaerobic infections). Examples of such infections are tooth abscess, abdominal (stomach) infections, leg ulcers, vaginal infections.
  • It works by killing or stopping the growth of the bugs that cause the infection.


  • The dose of metronidazole will be different for different people, depending on the type of infection.
  • As a guide, a typical dose for an adult is 400 milligrams two or three times a day, but your dose may be more or less than this.
  • Depending on the type of infection, your doctor will advise you on how long to take metronidazole for. This may be from 3 days to up to 2 weeks.
  • Always take your metronidazole exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much metronidazole to take, how often to take it, and any special instructions.

How to take metronidazole

  • Take your metronidazole tablets with a glass of water and meal. 
  • Space your metronidazole doses evenly through out the day.
  • Take metronidazole at the same times each day.
  • Do not drink alcohol while you are taking metronidazole and for 48 hours after finishing your course of treatment.
  • Drinking alcohol with metronidazole may make you feel very sick and cause other effects, such as hot flushes, headache and increased heart beat.
  • Keep taking metronidazole until you finish all the tablets, for as long as your doctor or pharmacist tells you to.
  • Do not stop taking metronidazole, even if you feel better after a few days, unless your doctor tells you to.
  • If you forget to take metronidazole, take it as soon as you remember.
  • 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.

Possible side effects

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

Side effects What should I do?
  • Feeling sick (nausea) or vomiting

  • Take metronidazole with food.
  • Do not drink alcohol while you are taking metronidazole.
  • Tell your doctor if troublesome.
  • Headache
  • Dry mouth
  • Food tastes different 
  • These are quite common when you first start taking metronidazole.
  • Tell your doctor if troublesome.
  • Allergic reaction such as skin rash, itching, swelling of the lips, face, and mouth or difficulty breathing
  • Tell your doctor immediately or ring HealthLine.


Metronidazole may interact with a few important medications or herbal supplements, so check with your doctor or pharmacist.

Learn more

Medsafe Consumer Information Sheet Trichazole

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