Medication Information Leaflet

What is this medication for?

Metronidazole is an antibiotic that is commonly used to treat infections of the gut. It may also be used for the treatment of certain parasitic infections and bacterial vaginal infections. Metronidazole may also be applied on the skin to treat skin conditions such as rosacea.

How should I take/use this medication?

Oral Metronidazole

  • Metronidazole may be taken with or after food.
  • Complete the course of antibiotics as prescribed by your doctor. Incomplete treatment may cause infections to happen again.
  • Do check with your healthcare professional before stopping your medication.

Metronidazole/Nystatin vaginal pessary

  • Place one vaginal pessary deep into your vagina. Do this at bedtime. You may wear a sanitary pad to prevent the medicine from getting onto your clothing. Do not use tampons.
  • The medication may come with an applicator specially designed to be used with the vaginal pessary.
  • Wash and dry your hands before administering the pessary.
  • Pull back the applicator plunger about 2.5cm.
  • Remove the pessary from its plastic wrapping. Insert the pessary into the cup at the end of the applicator.
  • Lie on your back with your knees drawn up towards your chest. Insert the applicator into your vagina as far as it will comfortably go.
  • Be sure the applicator is in the correct position in your vagina before you push the plunger.
  • Push the plunger fully to place the pessary in your vagina.
  • Remove the applicator. Wash with soap and warm water. Rinse thoroughly and dry.

Topical Metronidazole (gel)

  • Wash and dry your hands before and after using the medicine.
  • Clean and dry the area that you will be applying Metronidazole on. Apply a thin layer of the medicine.
  • Topical Metronidazole is usually applied 1 to 2 times a day. Follow your doctor's instructions.
  • Avoid your eyes, nose, mouth and lips when you apply Metronidazole on your skin. Wash with water if the medicine gets into any of these areas. Avoid applying onto broken or irritated skin as it can worsen the skin condition.

What should I do if I forget to take/use this medication?

If you forget to take a dose, take it as soon as you remember. If it is close to the time for your next dose, skip the missed dose and go back to your usual timing. Do not take two doses at the same time to make up for the missed dose.

What precautions should I take?

Inform your healthcare professional if:

  • You are allergic to this medication or any of the other ingredients of this medication.
  • You are pregnant, planning to become pregnant, or breastfeeding. Metronidazole crosses the placenta and may carry risk to the fetus, especially in the first trimester. Metronidazole can be present in significant amounts in the breast milk. It may still be used safely in pregnancy and breastfeeding. Risks and benefits regarding the use of Metronidazole during breastfeeding and pregnancy should be discussed with your doctor.
  • You have taken Disulfiram within the past two weeks.
  • You are taking any other medications, including supplements, traditional medications and herbal remedies.
  • You have liver disease, kidney disease or disease of the nervous system.

What are some common side-effects of this medication?

  • Nausea, vomiting, loss of appetite, having a metallic or unpleasant taste in your mouth
    • Take Metronidazole with or after food
  • Headache
    • May take pain relief medications
  • Dry skin, redness or itching, skin irritation (for Metronidazole gel only)
    • Use the gel a little less often or stop using it until the irritation settles down. If the irritation is severe or worsens, stop using the medication and seek medical advice
  • Darkening of urine, which is a harmless side effect on its own

What are some rare but serious side-effects that I need to seek medical advice immediately?

Very rarely, Metronidazole may cause severe side-effects that are generally reversible once the medication is stopped. Stop this medication and seek medical advice immediately if you develop any of these symptoms below.

Liver injury with symptoms such as:

  • Dark-coloured or tea-coloured urine with accompanied symptoms as below
  • Pale stools
  • Severe abdominal pain, nausea and vomiting
  • Loss of appetite
  • Yellowing of the skin and eyes

Neurological disturbances such as:

  • Confusion, hallucinations
  • Disturbances in sight and movements, light sensitivity
  • Numbness
  • Stiff neck, tremors, convulsions, uncontrolled muscle and eye movements

How do I know if I am allergic to this medication?

The symptoms of a drug allergy include one or more of the following. If you experience any of these symptoms, you should stop your medicine immediately and see your doctor.

  • Swollen face/eyes/lips/tongue
  • Difficulty in breathing
  • Skin rashes over your whole body

What food or medication should I avoid when I take this medication?

Avoid consuming alcohol during the course of antibiotics and for three days after completion of antibiotics. Drinking alcohol with Metronidazole causes an unpleasant reaction which may present with nausea, vomiting, abdominal pain, palpitations (fast heart rate), hot flushes, headaches.

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication out of reach from children.

How should I throw away this medication safely?

Pack the medication into a bag and bring it back to the pharmacy where you received the medication from.



If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on Jul 2021

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