Patient leaflet - Metronidazole 200 mg film-coated tablets
1. WHAT METRONIDAZOLE TABLETS IS AND WHAT IT IS USED FOR
In particular, tell your doctor if you are taking:
Metronidazole tablet contains metronidazole as active ingredient, which belongs to the group of medicines called antibiotics.
- anti-coagulants (blood thinning agents), such as warfarin. The dosage of warfarin may need to be reduced you are taking this drug.
It works by killing bacteria and parasites that cause infections in your body. It can be used to treat:
- Lithium for mental illness. If taken at the same time as metronidazole, the kidneys may be affected.
- infections, caused by bacteria of the blood, brain, bone, lung, stomach lining and pelvic area, following childbirth or in a wound following an operation
- medicines used to treat epilepsy, such as phenytoin, primidone, phenobarbitone.
- gum ulcers and teeth infections
- 5 fluorouracil for cancer
- infected leg ulcers or pressure sores
- Busulfan for leukaemia (cancer of the blood cells)
- urinary or genital infections caused by a parasite, Trichomonas
- Ciclosporin - to prevent the rejection of organs after transplant
- genital infection in women caused by bacteria
- Disulfram for alcoholism If you are not sure, talk to your doctor or pharmacist before taking metronidazole
- or prevent infections occurring after operations.
If you need any further information on your illness, speak to your doctor.
- Medicines that may cause heart rhythm disturbances (so-called QT prolongation which can be seen on ECG) such as:
2. WHAT YOU NEED TO KNOW BEFORE YOU TAKE METRONIDAZOLE TABLETS
- certain anti-arrhythmics (medicines for heart rhythm disorders)
- certain antibiotics
- medication primarily used to manage psychosis (including delusions, hallucinations, paranoia or disordered thought)
Do not take Metronidazole tablets;
If you are allergic (hypersensitive) to metronidazole, nitroimidazoles (e.g. tinidazole) or any of the other ingredients of this medicine (listed in section 6).
Metronidazole Tablets with food and drink
Do not drink any alcohol while you are taking Metronidazole and for 48 hours after finishing your course. Drinking alcohol while using Metronidazole might cause unpleasant side effects, such as feeling sick (nausea), being sick (vomiting), stomach pain, hot flushes, very fast or uneven heartbeat (palpitations) and headache.
Signs of an allergic reaction include: a rash, swallowing or breathing problems, swelling of your lips, face, throat or tongue
Do not take Metronidazole if any of the above applies to you. If you are not sure, talk to your doctor or pharmacist before taking Metronidazole. Warnings and precautions
Pregnancy and breast feeding
Tell your doctor before using Metronidazole if:
The highest risk for occurrence of serious skin reactions is within one week, typically, within 48 hours after start of treatment. If you develop a serious rash or any of these skin symptoms, stop taking Metronidazole and contact your doctor or seek medical attention immediately.
- You are pregnant, might become pregnant or think you may be pregnant. Metronidazole should not be taken during pregnancy unless considered absolutely necessary
- You are breast-feeding. It is better not to use Metronidazole if you are breast-feeding. This is because small amounts may pass into the mother's milk.
Serious skin reactions including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), acute generalised exanthematous pustulosis (AGEP) have been reported with the use of metronidazole.
Ask your doctor or pharmacist for advice before taking any medicine. Driving and using machines While taking Metronidazole you may feel sleepy, dizzy, confused, see or hear things that are not there (hallucinations), have fits (convulsions) or temporary eyesight problems (such as blurred or double vision), vertigo. If this happens, do not drive or use any machinery or tools. Test
- SJS/TEN can appear initially as reddish target-like spots or circular patches often with central blisters on the trunk. Also, ulcers of the mouth, throat, nose, genitals and eyes (red and swollen eyes) can occur. These serious skin rashes are often preceded by fever and/or flu-like symptoms. The rashes may progress to widespread peeling of the skin and life- threatening complications or be fatal.
AGEP appears at the initiation of treatment as a red, scaly widespread rash with bumps under the skin and blisters accompanied by fever. The most common location: mainly localised on the skin folds, trunk, and upper extremities.
If you are going to have a blood test, tell the doctor or nurse performing the test that you are using Metronidazole . Metronidazole can affect the results of some blood tests.
If you have any further questions on the use of this medicine, ask your doctor or pharmacist.
Talk to your doctor or pharmacist before taking Metronidazole Tablets:
if you have or have ever had a liver problem
Your doctor may wish to carry out some tests if you have been using this medicine for more than 10 days.
- if you are having kidney dialysis (see section 3: 'people having kidney dialysis')
- if you have a disease of nervous system
3. HOW TO TAKE METRONIDAZOLE TABLETS Taking your medicine
If you are not sure if any of the above applies to you, talk to your doctor or pharmacist before taking your medicine. Do this even if they have applied in the past.
Always take metronidazole exactly as your doctor has told you. It is important to finish a full course of treatment. The length of a course will depend on your needs and the illness being treated.
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.
Check with your doctor or pharmacist if you are not sure.
- Swallow the tablets whole with a drink of water
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.
- Do not crush or chew the tablets
- Take these tablets during or just after a meal
- The dose of metronidazole will depend on your needs and the illness being treated
Tell your doctor immediately and stop taking metronidazole if you develop:
Stomach pain, annorexia, nausea, vomiting, fever, malaise, vertigo, fatigue, jaundice, dark urine, putty or mastic coloured stools or itching. Other medicines and Metronidazole Tablets
- The length of your treatment will depend on the type of illness you have and how bad it is
The usual dose for adults and children is given below:
Please tell your doctor or pharmacist if you are taking or have recently taken any other medicines.
To treat bacterial infection
Adults
This includes medicines obtained without a prescription, including herbal medicines. This is because Metronidazole can affect the way some other
- The initial dose is 800mg
- After 8 hours take another dose of 400mg and repeat this dose every 8 hours METRONIDAZOLE 200mg/400mg/500mg fi lm coated tablets Size: 210x297 mm (Amended on 01/09/2026) Main Heading type style: 14.3pt Helvetica Bold Condensed Caps Sub Heading type style: 11pt Helvetica Bold Condensed Caps Text type style: 8.8pt Helvetica Medium Condensed & Bold Condensed
METRONIDAZOLE 200mg/400mg/500mg fi lm coated tablets Size: 210x297 mm (Amended on 01/09/2026) Main Heading type style: 14.3pt Helvetica Bold Condensed Caps Sub Heading type style: 11pt Helvetica Bold Condensed Caps Text type style: 8.8pt Helvetica Medium Condensed & Bold Condensed
Children
- Your doctor will work out how much your child should take depending on their weight
- If your child is a baby under 8 weeks of age, your doctor will give them one daily dose or two separate doses 12 hourly
- repeat the dose every 8 hours
To prevent infections from happening after surgery
Adults
- Start Taking metronidazole Tablets 24 hours before your operation
- Take 400 mg of metronidazole every 8 hours
- After the operation you may be given Metronidazole either through a drip into a vein or rectally as a suppository until you are able to take tablets again
Children
- Start giving your child Metronidazole Tablets 1-2 hours before their operation
- Your doctor will work out how much your child should take depending on their weight
- After the operation your child may be given Metronidazole either through a drip into a vein or rectally as a suppository until they are able to take tablets again
Other types of infections
For treatment of other infections caused by parasites and some bacteria your doctor will decide how much metronidazole you need to take and how often. This will depend on your illness and how bad it is. The pharmacist's label on the packaging will tell you how many tablets to take and how often to take them.
People having kidney dialysis
Kidney dialysis removes metronidazole from your blood. If you are having kidney dialysis you must take this medicine after your dialysis treatment. People with liver problems
Your doctor may tell you to use a lower dose or to use the medicine less often. If you take more Metronidazole Tablets than you should
If you take more metronidazole than you should, contact your doctor or nearest hospital emergency department immediately. Always take the box, this leaflet and any tablets that are left over with you, if you can. This is so the doctor knows what you have taken.
If you forget to take Metronidazole Tablets:
If you miss a dose, take it as soon as you remember and carry on as before. If it is almost time for your next dose, skip the forgotten dose and continue as usual. Do not take a double dose to make up for a forgotten dose. If you stop taking Metronidazole:
You should only stop taking Metronidazole if your doctor tells you to. It is essential to take the medicine and not to stop and start as this could cause unwanted side effects.
If you have any further questions on the use of this medicine, ask your doctor or pharmacist.
4. POSSIBLE SIDE EFFECTS
Like all medicines, this medicine can cause side effects although not everybody gets them.
Stop taking metronidazole and see a doctor or go to a hospital straight away if you notice any of the following serious side effects – you may need urgent medical treatment:
- You develop a red, scaly widespread rash with bumps under the skin and blisters accompanied by fever at the initiation of treatment (acute generalised exanthematous pustulosis). Stop using metronidazole if you develop these symptoms and contact your doctor or seek medical attention immediately. See also section 2.
- If you get swelling of the hands, feet, ankles, face, lips or throat which may cause difficulty in swallowing or breathing. You could also notice an itchy, lumpy rash (hives) or nettle rash (urticaria).This may mean you are having an allergic reaction to Metronidazole.
- You develop skin rashes including Stevens-Johnson syndrome or toxic epidermal necrolysis. These can appear as reddish target-like spots or circular patches often with central blisters on the trunk, skin peeling, ulcers of the mouth, throat, nose, genitals and eyes and can be preceded by fever and flu-like symptoms. Stop using metronidazole if you develop these symptoms and contact your doctor or seek medical attention immediately. See also section 2.
- A serious but very rare side effect is a brain disease (encephalopathy). Symptoms vary but you might get a fever, stiff neck, headache, see or hear things that aren't there. You might also have problems using your arms and legs, problems with speaking or feel confused.
- Unexpected infections, mouth ulcers, bruising, bleeding gums, or severe tiredness. This could be caused by a blood problem.
- Yellowing of the skin and eyes. This could be due to a liver problem (jaundice)
- Severe stomach pain which may reach through to your back (pancreatitis) Tell your doctor or pharmacist if you notice any of the following side effects:
Very rare (affects less than 1 in 10 000 people)
- Mental problems such as feeling confused and seeing or hearing things that are not there (hallucinations)
- Fits (convulsions)
Feeling sleepy or dizzy
- Problems with your eyesight such as blurred or double vision
- Headache
- Liver problems including life threatening liver failure (hepatocellular liver injury)
- Darkening of the urine
- Pains in the muscles or joints
- Skin rash or flushing
Not known (frequency cannot be estimated from the available data)
- PRES - A brain condition with symptoms such as headache, confusion, visual disturbance and seizures
- Feeling sick (nausea), being sick (vomiting), upset stomach, stomach pain or diarrhea
- Feeling depressed
- Numbness, tingling, pain, or a feeling of weakness, in the arms or legs
- Unpleasant taste in the mouth
- Furred tongue
- Loss of appetite
- Fever
- Pain in your eyes (optic neuritis)
- A group of symptoms together including: fever, nausea, vomiting, headache, stiff neck and extreme sensitivity to bright light. This may be caused by an inflammation of the membranes that cover the brain and spinal cord (meningitis)
- Hearing impairment/ hearing loss
- Ringing in the ears (tinnitus)
- You get a rash or skin discolouration with or without raised areas which often reoccurs at the same location each time the drug is taken
- Neurological disorder called cerebellar syndrome, which symptoms can include difficulties in coordinating movements, speaking and/or walking, involuntary movement of the eyes, and shaking. It may resolve upon stopping the treatment.
- Acute liver failure in patients with Cockayne Syndrome (see section 2 ‘Warnings and precautions’)
- Heart rhythm disturbances (so-called QT prolongation which can be seen on ECG), particularly when metronidazole is used with other medicines that may cause heart rhythm disturbances.
- Vertigo (spinning sensation)
Reporting of side effects
If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.
By reporting side effects you can help provide more information on the safety of this medicine.
5. HOW TO STORE METRONIDAZOLE TABLETS
- Keep this medicine out of the sight and reach of children.
- Do not store above 25°C in original packaging. Protect from light
- Do not use this medicine after the expiry date shown on the pack. The expiry date refers to the last day of that month.
- Ask your pharmacist how to dispose of medicines no longer required. Do not dispose of medicines by flushing down a toilet or sink or by throwing out with your normal household rubbish. This will help protect the environment.
6. CONTENTS OF THE PACK AND OTHER INFORMATION
What Metronidazole tablet contains
200mg: Each film-coated tablet contains 200 mg of Metronidazole as the active substance
400mg: Each film-coated tablet contains 400 mg of Metronidazole as the active substance
500mg: Each film-coated tablet contains 500 mg of Metronidazole as the active substance
The other ingredients are: Anhydrous calcium hydrogen phosphate, Maize starch, Povidone, Crospovidone, Microcrystalline cellulose, Colloidal anhydrous silica, Magnesium stearate, Hypromellose and Polyethylene glycol What Metronidazole tablet looks like and contents of the pack
200mg: white to off white colored, caplet shaped (14.20 x 5.70mm) film-coated tablets, debossed “200” on one side and plain on other side. 400mg: white to off white colored, caplet shaped (17.00 x 6.00 mm) film-coated tablets, debossed “400” on one side and plain on other side. 500mg: white to off white colored, (13 mm) round convex shaped film-coated tablets, debossed “500” on one side and plain on other side. Metronidazole tablets are available in Alu-PVC/PVDC blister packs of 20 and 21 tablets
Not all pack sizes may be marketed.
Marketing Authorisation Holder and Manufacturer
Marketing Authorisation Holder
RxFarma, Colonial Way, Watford, Hertfordshire, WD24 4YR Manufacturer
Rx Farma Limited, Unit 3, Colonial Way, Watford,
Hertfordshire, WD24 4YR, United Kingdom
If you would like this leaflet in different format or want to report any side effects please contact marketing authorisation holder listed above. This leaflet was last revised in September 2026