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Active substance(s): METRONIDAZOLE

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Read all of this leaflet carefully before you start taking
this medicine.
• Keep this leaflet. You may need to read it again.
• If you have further questions, please ask your doctor or
• This medicine has been prescribed for you. Do not
pass it on to others. It may harm them, even if their
symptoms are the same as yours.
• 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.
In this leaflet:
1. What Flagyl is and what it is used for
2. Before you take Flagyl
3. How to take Flagyl
4. Possible side effects
5. How to store Flagyl
6. Further information


The name of this medicine is Flagyl 200mg or 400mg
Tablets (called Flagyl in this leaflet). Flagyl contains a
medicine called metronidazole. This belongs to a group of
medicines called antibiotics.
It works by killing bacteria and parasites that cause
infections in your body.
It can be used to:
• Treat infections of the blood, brain, lung, bones, genital
tract, pelvic area, stomach and intestines
• Treat gum ulcers and other dental infections
• Treat infected leg ulcers and pressure sores
• Prevent infections after surgery
If you need any further information on your illness, speak
to your doctor.


Do not take Flagyl and tell your doctor if:
• You are allergic (hypersensitive) to metronidazole,
nitroimidazoles (e.g. tinidazole) or any of the other
ingredients in your medicine (listed in Section 6:
Further information).
Signs of an allergic reaction include: a rash, swallowing
or breathing problems, swelling of your lips, face,
throat or tongue.
Do not take Flagyl if any of the above apply to you. If you
are not sure, talk to your doctor or pharmacist before
taking Flagyl.
Take special care with Flagyl and check with your
doctor or pharmacist before using your medicine if:
• You have or have ever had a liver problem.
• You are having kidney dialysis (see section 3: ‘People
having kidney dialysis’)
• You have a disease of the nervous system
If you are not sure if any of the above apply to you, talk to
your doctor or pharmacist before taking your medicine.
Do this even if they have applied in the past.
Cases of severe liver toxicity/acute liver failure, including
cases with a fatal outcome, in patients with Cockayne
syndrome have been reported with Flagyl.
If you are affected by Cockayne syndrome, your doctor
should also monitor your liver function frequently while
you are being treated with Flagyl and afterwards.
Tell your doctor immediately and stop taking Flagyl if you
• 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. This includes
medicines obtained without a prescription, including
herbal medicines. This is because Flagyl can affect the
way some other medicines work. Also, some other
medicines can affect the way Flagyl works.
In particular tell your doctor if you are taking any of the
following medicines:
• Medicines used to thin the blood such as warfarin
• Lithium for mental illness
• Phenobarbital or phenytoin for epilepsy
• 5 fluorouracil for cancer
• Busulfan for leukaemia (cancer of the blood cells)
• Ciclosporin – to prevent the rejection of organs after
• Disulfiram for alcoholism
If you are not sure, talk to your doctor or pharmacist
before taking Flagyl.
Taking Flagyl with food and drink
Do not drink any alcohol while you are taking Flagyl and
for 48 hours after finishing your course. Drinking alcohol
while using Flagyl 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.
Pregnancy and breast-feeding
Tell your doctor before using Flagyl if:
• You are pregnant, might become pregnant or think you
may be pregnant. Flagyl should not be taken during
pregnancy unless considered absolutely necessary.
• You are breast-feeding. It is better not to use Flagyl if
you are breast-feeding. This is because small amounts
may pass into the mother’s milk.
Driving and using machines
While taking Flagyl 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). If this happens, do not drive
or use any machinery or tools.
Your doctor may wish to carry out some tests if you have
been using this medicine for more than 10 days.


Taking your medicine
Always take Flagyl 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.
Check with your doctor or pharmacist if you are not sure.
• Swallow the tablets whole with a drink of water
• Do not crush or chew the tablets
• Take these tablets during or just after a meal
• The dose of Flagyl will depend on your needs and the
illness being treated
• 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:
To treat bacterial infection
• The initial dose is 800mg
• After 8 hours take another dose of 400mg and
repeat this dose every 8 hours
• Your doctor will work out how much your child
should take depending on their weight
• Repeat the dose every 8 hours
• 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
To prevent infections from happening after surgery
• Start Taking Flagyl Tablets 24 hours before your
• Take 400 mg of Flagyl every 8 hours
• After the operation you may be given Flagyl either
through a drip into a vein or rectally as a suppository
until you are able to take tablets again

• Give your child Flagyl Tablets 1-2 hours before their
• Your doctor will work out how much your child
should take depending on their weight
• After the operation your child may be given Flagyl
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 Flagyl 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 Flagyl 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 Flagyl than you should
If you take more Flagyl than you should, tell your doctor
or go to your nearest hospital casualty department
straight away. Take the pack and any tablets left with you.
This is so the doctor knows what you have taken.
If you forget to take Flagyl
If you forget to take Flagyl, take it as soon as you
remember. However, if it is almost time for your next
dose, skip the missed dose. Do not use a double dose to
make up for a forgotten dose.


Like all medicines, Flagyl can cause side effects, although
not everybody gets them.
Stop taking Flagyl and see a doctor or go to a hospital
straight away 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 Flagyl.
• A serious but very rare side effect is a brain disease
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.
• You develop skin rashes with blistering, peeling or bleeding
of the skin around the lips, eyes, mouth, nose, and genitals.
You may also have flu-like symptoms and a high
temperature. These could be signs of something called
‘Stevens-Johnson Syndrome or toxic epidermal necrolysis’.
Talk to your doctor straight away if you notice the
following side effects.
• Yellowing of the skin and eyes. This could be due to a
liver problem (jaundice).
• Unexpected infections, mouth ulcers, bruising,
bleeding gums, or severe tiredness. This could be
caused by a blood problem.
• 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)
• Fits (convulsions)
• Mental problems such as feeling confused and seeing
or hearing things that are not there (hallucinations)
• Problems with your eyesight such as blurred or double
• Skin rash or flushing
• Headache

Darkening of the urine
Feeling sleepy or dizzy
Pains in the muscles or joints
Liver problems including life-threatening liver failure
(hepatocellular liver injury)
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, stomach pain or diarrhoea
• Loss of appetite
• Fever
• Feeling depressed
• 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
• 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
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:
By reporting side effects you can help provide more
information on the safety of this medicine.


• Keep your medicine in a safe place and out of the
reach and sight of children.
• Store below 30º C in the original packaging (protect
from light)
• Do not use this medicine after the expiry date shown
on the pack.
• 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.


What Flagyl Tablets contain
Each tablet contains 200mg or 400mg of metronidazole
as the active substance.
Other ingredients are: calcium hydrogen phosphate (E341),
starch maize, povidone K30 (E1201) and magnesium stearate.
The coating of the tablets contains: Pharmacoat 615 (E464)
and Macrogol 400.
What Flagyl Tablets look like and contents of the pack
Flagyl 200mg and 400mg Tablets are white to off-white
biconvex film coated tablets with ‘Flagyl 200’ or ‘Flagyl
400’ printed on one side.
Flagyl 200mg Tablets are available in aluminium/plastic
blister packs of 21 tablets and HDPE bottles of 100 and
250 tablets.
Flagyl 400mg Tablets are available in aluminium/plastic
blister packs of 14 tablets and HDPE bottles of 100 tablets.
The Marketing Authorisation Holder is: Zentiva, One
Onslow Street, Guildford, Surrey, GU1 4YS, UK
The Manufacturer is: Famar Health Care Services Madrid,
S.A.U., Avda. Leganés, 62,Alcorcón 28923 (Madrid) Spain
This leaflet was last updated in November 2016
“Flagyl” and “Zentiva” are registered trademarks. ©2016

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.