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Metrolyl (Metronidazole) suppositories 1 g – patient leaflet, side effects, dosage

Last updated: · Text from the MHRA, as of · About this document

Medicine status: No longer supplied Details

Medicine strength:
1 g
Still supplied:
The same active substance, strength and form in the NHS Dictionary of Medicines and Devices (dm+d). Ask your pharmacist or doctor before changing to another make.
Contains active substance:

Patient leaflet - Metrolyl (Metronidazole) suppositories 1 g

1 What Metrolyl® are and what they are used for

The name of your medicine is Metrolyl® (Metronidazole) Suppositories 500 mg or 1 g. Metrolyl® (Metronidazole) Suppositories are antibacterials used to treat infections.

Metrolyl® works by killing the bacteria in our body.

It can be used to treat:

  • Treat infections in the blood, brain, lung, bones, genital tract, pelvic area and stomach
  • Prevent infections after surgery

If you need any further information about your illness, speak to your doctor.

2 Before you use Metrolyl®

Do not use Metrolyl® if:

  • You are allergic to metronidazole, or any of the other ingredients in this medicine (see section 6 Further Information). Signs of an allergic reaction are: rash, swallowing or breathing problems, swelling of the face, lips, tongue or throat. Do not use Metrolyl® if any of the above applies to you, if you are not sure ask your doctor or pharmacist.

Take special care with Metrolyl®:

  • If you have or have had a liver disease.
  • If you have kidney failure and are having dialysis (see section 3. People having kidney dialysis).
  • If you have a disease of the nervous system.

If you are not sure speak to you doctor or pharmacist.

Cases of severe liver toxicity/acute liver failure, including cases with a fatal outcome, in patients with Cockayne syndrome have been reported with product containing metronidazole.

If you are affected by Cockayne syndrome, your doctor should also monitor your liver function frequently while you are being treated with metronidazole and afterwards.

Tell your doctor immediately and stop taking metronidazole if you develop:

  • Stomach pain, anorexia, nausea, vomiting, fever, malaise, fatigue, jaundice, dark urine, putty or mastic coloured stools or itching.

Taking other medicines:

Please tell your doctor or pharmacist if you are taking or have recently taken any other medicines, including medicines obtained without a prescription. This includes herbal medicines.

It is important that you tell your doctor if you are taking:

  • Phenobarbitone, primidone, phenytoin (used for epilepsy and convulsions),
  • Anticoagulants such as warfarin (used to prevent blood clots),
  • Lithium (used to treat depressive illness),
  • Cimetidine (used to treat stomach ulcers),
  • Cytotoxics such as fluorouracil and busulfan (used to treat cancer),
  • Disulfiram (used to treat alcohol abuse),
  • Ciclosporin to prevent rejection of organs after transplant.

If you are not sure speak to your doctor or pharmacist before using Metrolyl®.

Using Metrolyl® with food and drink

Do not drink alcohol while taking metronidazole and for 48 hours after the course of the medicine has finished as you may get an unpleasant reaction, such as feeling or being sick, stomach pain, hot flushes, palpitations (sensation of feeling your heart beating) and headaches.

Pregnancy and breast-feeding

Talk to your doctor before using Metrolyl® (Metronidazole) Suppositories if you are pregnant or think you may be pregnant.

Do not use Metronidazole while breast-feeding as it is secreted in breast milk in small amounts.

Driving and using machines

If you experience any dizziness, drowsiness, hallucinations (seeing or hearing things that are not there), confusion, have fits (convulsions), blurred or double vision, if you are affected do not drive or operate machinery until you have consulted a doctor.

Your doctor may want to carry out some laboratory tests if you are using this medicine for more than 10 days.

3 How to use Metrolyl®

Always use Metrolyl® exactly as your doctor has told you. You should check with your doctor or pharmacist if you are not sure.

The usual doses are shown below. Doctors sometimes prescribe different doses to these: if this applies to you, discuss it with the doctor, if you have not already done so.

Treatment with metronidazole will normally be for 7 days. Shorter or longer treatment may be prescribed if your doctor feels this is necessary. If treatment is to continue for longer than 10 days your doctor will keep a close eye on you.

Metrolyl® should be inserted into the anus (rectum). They may be given on their own or with other medicines which kill bacteria.

The usual dose is:

  • Suppositories are normally used for 3 days
  • As soon as possible after starting treatment with the suppositories, your doctor will suggest changing to a medicine taken by mouth.
  • After 3 days, if you r doctor wants your child to continue using the suppositories, you will probably be told to use the suppositories every 12 hours.

The usual dose for adult and children using suppositories are below:

For the treatment of infections

Metrolyl® may be used to treat a number of different infections. Your doctor will decide on the appropriate dosage depending on the type of infection.

The usual dosage is as follows:

Adults and children over 10 years:

  • Use one 1 g suppository every 8 hours for 3 days. See above for the dosing over 3 days.

Children aged 5 – 10 years:

  • Use one 500 mg suppository, every 8 hours for 3 days See above for the dosing over 3 days.

Children aged 1-5 years:

  • Use one half of a 500 mg suppository, every 8 hours for 3 days See above for the dosing over 3 days.

Infants under 1 year old:

  • Use one quarter of a 500 mg suppository, every 8 hours for 3 days See above for the dosing over 3 days.

To prevent infections form happening after surgery

Adults and children over 10 years

  • Use one 1 g suppository 2 hours before surgery.
  • Repeat every 8 hours up to 3 days. See above for dosing after 3 days.

Children aged 5-10 years

  • Use one 500 mg suppository 2 hours before surgery.
  • Repeat every 8 hours up to 3 days. See above for dosing after 3 days.

People having kidney dialysis

Your doctor may tell you to stop using Metrolyl® during dialysis and start using it again once you gave finished.

People with liver problems

Your doctor may give you a lower dose or tell you to use this medicine less often.

If you use more Metrolyl® than you should

If you use more suppositories than you should, tell your doctor or go to a hospital casualty department straight away, taking the pack and the suppositories you have left with you, to show your doctor what you have used.

If you forget to use Metrolyl®

If you forget to take a dose, take the missed dose as soon as you remember. If is nearly time for your next dose, have a single dose straight away and skip the next.

If you stop using Metrolyl®

You should always complete the prescribed course, unless your doctor tells you to stop.

If you have any further questions on the use of this product, ask your doctor or pharmacist.

4 Possible side effects

Like all medicines, Metrolyl® can cause side effects, although not everybody gets them.

Stop using Metrolyl® and seek immediate medical help if:

  • You get swelling of the hands, feet, ankles, face, lips, mouth or throat, this could cause breathing or swallowing problems, itchy lumpy rash (hives) or nettle rash (urticaria). This could be caused by an allergic reaction to Metrolyl®.
  • A very rare serious side effect is a brain disease (encephalopathy, the symptoms include stiff neck, fever, headaches, seeing or hearing things that are not there, confusion, problems using your arms or legs, speech problems.

Talk your doctor straight away if you notice the following side effects:

  • Yellowing of the whites of the eyes and the skin, this could be due to jaundice (liver problem)
  • Unexpected infections, mouth ulcers, bruising, bleeding gums or severe tiredness (could be blood problems)
  • Severe stomach pain which may reach through to your back (pancreatitis)

Tell your doctor or pharmacist f you notice any of the following side effects:

Very rare (effects less than 1 in 10,000 people)

  • Fits (convulsions)
  • Darkening of the urine
  • Feeling sleepy or dizzy
  • Pains in the muscles or joints

Not known (frequency cannot be estimated from the available data)

  • Numbness, tingling, pain or a feeling of weakness in the arms or legs
  • Unpleasant taste in the mouth
  • Furred tongue
  • Feeling sick (nausea), being sick (vomiting, upset stomach pain or diarrhoea
  • Loss of appetite
  • Fever
  • Feeling depressed
  • Acute liver failure in patients with Cockayne Syndrome (see section 2 “Warnings and precautions”)

If any of the side effects gets serious, or if you notice any side effects not listed in this leaflet, please tell your doctor or pharmacist.

5. How to store Metrolyl®

Keep all medicines out of the reach and sight of children.

Do not use Metrolyl® (Metronidazole) Suppositories 500 mg or 1 g after the expiry date shown on the label. The expiry date refers to the last day of that month. Any out of date medicines should be returned to your pharmacist for disposal.

Do not store above 25°C. Protected from light.

If you notice any defects in the suppositories, take them to your pharmacist for advice before using them.

Medicines should not be disposed of via wastewater or household waste. Ask your pharmacist how to dispose of medicines no longer required. These measures will help to protect the environment.

6. Further Information

What Metrolyl® contain:

Each suppository contains 500 mg or 1 g of the active ingredient metronidazole BP.

The other ingredient is hard fat suppository base.

The suppositories are supplied in packs of 10.

Marketing Authorisation Holder and Manufacturer

The marketing authorisation holder and manufacturer is:

Sandoz Ltd, Frimley business Park, Frimley, Camberley, Surrey, GU16 7SR

This leaflet was last revised on: 12/12/2022.

About this document

Source: MHRA - Medicines and Healthcare products Regulatory Agency (products.mhra.gov.uk) · Marketing authorisation: PL 04416/0054

Last revision stated in the text: 12 December 2022 · MHRA data as of 13 October 2026

Found a mistake? Tell us on the contact page.

The information on this site does not replace the advice of a doctor or pharmacist.

Facts about Metrolyl (Metronidazole) suppositories 1 g

Active substance Metronidazole
Strength 1 g
Pharmaceutical form Suppository
White opaque suppository
How is it taken Rectal
Is it available? No, all its packs are listed as discontinued (NHS Dictionary of Medicines and Devices – not a record of current supplies)
Drug group (ATC)
  1. P Antiparasitic products, insecticides and repellents
    1. P01 Antiprotozoals
      1. P01A Agents against amoebiasis and other protozoal diseases
        1. P01AB Nitroimidazole derivatives, antiprotozoal agents against amoebiasis and other protozoal diseases
          1. P01AB01 metronidazole
Marketing authorisation PL 04416/0054 (first authorised 25 May 1982)
Marketing authorisation holder Sandoz Limited
Codes BNF 05011100

Sources: the MHRA product information (products.mhra.gov.uk) and the NHS Dictionary of Medicines and Devices (dm+d), release 10.2.0 of 19 October 2026, NHS Business Services Authority. Contains public sector information licensed under the Open Government Licence v3.0.