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Metformin 500mg
and 850mg Tablets
Metformin hydrochloride
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 any further questions, 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 get serious, or if you notice any
side effects not listed in the leaflet, please tell your doctor
or pharmacist.

In this leaflet:
1 What Metformin Tablets are and what they are
used for
2 Before you take Metformin Tablets
3 How to take Metformin Tablets
4 Possible side effects
5 How to store Metformin Tablets
6 Further information

1 What Metformin Tablets are and what they are
used for

Metformin hydrochloride is one of a group of medicines called
oral hypoglycaemics which work by reducing the level of sugar
in the blood.
Metformin Tablets are an anti-diabetic medicine used to treat
Type 2 (non-insulin dependent) diabetes. This is the type of
diabetes that usually develops in adulthood which is not severe
enough to need insulin but does not respond to dietary measures

2 Before you take Metformin Tablets
Do not take Metformin Tablets:

• If you are allergic to any of the ingredients in this medicine.
• If you have a heart disorder or have suffered from heart failure or
a recent heart attack.
• If you have a problem with your liver or kidneys.
• If you have diabetic ketoacidosis (complication of diabetes
with rapid weight loss, nausea or vomiting), or have suffered a
diabetic coma.
• If you have severe circulatory problems causing frequent leg
cramps or leg ulcers that do not heal, or breathing problems.
• If you have a severe infection, injury or trauma (shock), a fever or
are unwell in any way.
• If you are suffering excessive loss of body water.
• If you drink alcohol excessively
• If you are pregnant or you are breast-feeding.
Metformin Tablets should not be taken by children.

Take special care with Metformin Tablets:

Tell your doctor before you start taking these tablets:
• If you are elderly
• If you taking other antidiabetic drugs (e.g. insulin, guar gum or a
sulphonylurea drug such as glibenclamide).
• If you have had or about to have surgery under general
anaesthetic. Your doctor will advise you when it is safe to start
taking them again after the surgery.
• You are on a very low calorie diet (less than 1000 calories a day)
or are fasting. This could increase the chances of you getting
a very rare, but serious side effect called lactic acidosis (see
section 4).
The amount of sugar in your blood or urine should be checked
regularly. Your doctor will also check your kidneys are working
properly. This should be done at least once a year (more often if
you are elderly or have kidney problems).
• If you are going to undergo scans in combination with injectable
dyes. They should not be resumed for at least 48 hours after the
procedure and only when your kidneys have been checked to
show that they are functioning normally.

Taking other medicines:

Please tell your doctor or pharmacist if you are taking or have
recently taken any other medicine. This includes medicines
obtained without a prescription, including herbal medicines. This
is because metformin can affect the way some other medicines
work. Also, some medicines can affect the way metformin works.

In particular, tell your doctor or pharmacist if you are
taking any of the following medicines:

• Medicines for high blood pressure (hypertension) such as water
tablets (diuretics), ACE inhibitors (such as enalapril)
• Medicines for asthma such as salbutamol or formoterol
• Medicines used for inflammation called steroids
• Non steroidal anti inflammatory drugs (such as salcylates
or pyrazolones)
• Mono Amino oxidase inhibitors
• Cyclophosphamide and its derivatives
• Cimetidine
• Phenprocoumone
• Icotinic acid and its derivatives
• Oxytetracycline
• Thyroid harmones
• Phenothiazines
• Diazoxide
• Glucagon
If any of the above apply to you (or you are not sure), talk to your
doctor or pharmacist before taking metformin.

Taking Metformin Tablets with food and drink:

• You need to eat carbohydrates regularly throughout the day.
• If your doctor has given you advice on your diet, you need to
continue to follow this.
• Do not drink large amounts of alcohol or take medicines
containing alcohol while taking metformin.
continued over page

Pregnancy and Breastfeeding:
Tell your doctor if you are, you think you might be or are planning
to become pregnant. Your doctor will advise you to discontinue
these tablets. You should not use Metformin Tablets if you are
breast-feeding or are planning to breast-feed your baby.
Driving and using machines:
Metformin Tablets on their own should not affect your ability
to drive, but if you are also taking any other medicines which
lower the blood sugar it is possible that their combined effects
could make you feel faint, dizzy, weak or jittery. If this happens
you should not drive or operate any machinery until you have

Important information about some of the ingredients
of Metformin Tablets
Metformin Tablets contain propylene glycol which may cause
allergic reactions.

3 How to take Metformin Tablets

Always take Metformin Tablets exactly as your doctor has told
you. You should check with your doctor or pharmacist if you are
not sure.

Taking this medicine

• Swallow the tablets whole with a glass of water.
• Do not crush or chew the tablets.
• Take metformin with or after food. This lowers the chance of
getting an upset stomach.
• Try to take your medicine at the same time each day so that it
becomes part of your daily routine.
• Keep taking metformin until your doctor tells you to stop. Do not
stop taking metformin just because you feel better. If you stop
your illness may get worse.
Treatment usually starts with a dose of one 500mg tablet three
times a day or one 850mg tablet twice a day. Your doctor may
then increase the dose in a stepwise manner until the right dose
for you is found. After a while your doctor may then be able to
reduce the dose. The dose needed varies between different
people. The maximum doses are six 500mg tablets or three
850mg tablets daily.

If you take more Metformin Tablets than you should:
If you swallow too many tablets or someone else accidentally
takes your medicine, contact your doctor, pharmacist or nearest
hospital straight away.
Remember to take the pack and any remaining tablets with you.
This is so the doctor knows what you have taken.
The following effects may happen if you take too much
unexpected weight loss, feeling very sick or being very sick, very
fast breathing which you cannot stop, stomach pains or feeling
cold. You may have something called lactic acidosis. The doctor
may use a method called ‘haemodialysis’ to remove the extra
lactate and metformin from your body.

If you forget to take Metformin Tablets:

Try to take Metformin Tablets daily as prescribed. However, if you
miss a dose take it as soon as you remember unless it is nearly
time for the next dose. Do not take a double dose to make up for
the forgotten one.

If you stop taking Metformin Tablets:

Do not stop taking Metformin Tablets without first discussing it
with your doctor.
If you have any further questions on the use of Metformin Tablets
ask your doctor or pharmacist.

4 Possible side effects

Like all medicines, Metformin Tablets can cause side effects,
although not everyone gets them.

Stop taking metformin and see a doctor or go to a
hospital straight away if you get any of the following
very rare side effects:

• unexpected weight loss
• feeling very sick (nausea) or being very sick (vomiting)
• very fast breathing which you cannot stop
• stomach pains or feeling cold
This may mean you have something called “diabetic ketoacidosis”
or “lactic acidosis”. These can be signs of serious problems with
your diabetes. If this happens, see a doctor as you will need
treatment straight away.

Other side effects:

Very common (affects more than 1 in 10 people)
• Stomach problems such as feeling sick (nausea), being sick
(vomiting), diarrhoea, stomach pain and loss of appetite. These
side effects are most likely to happen at the start of treatment.
• They usually last for a short time. It helps to take the dose with
or after a meal.
Common (affects less than 1 in 10 people)
• taste of metal in your mouth
Very rare (affects less than 1 in 10,000 people)
• skin rash (including redness, itching, hives).
• low levels of vitamin B12. Over time this may lead to
anaemia, a sore mouth or tongue or possibly numbness or
tingling in the limbs.
• liver problems, abnormal liver function tests and hepatitis
(inflammation of the liver) that may result in jaundice. If
you notice yellowing of the eyes/skin contact your doctor
If any of the side effects gets serious, or if you notice any
side effects not listed in the leafelt, please tell your doctor or

5 How to store Metformin Tablets

Keep out of the reach and sight of children.
Do not use Metformin Tablets after the expiry date which is stated
on the carton.
Do not store the tablets above 25°C.

6 Further information

What Metformin Tablets contain

The active substance is 500mg or 850mg of metformin
The other ingredients are sodium starch glycollate, maize starch,
povidone, colloidal anhydrous silica, magnesium stearate. The
film coating is made up of hypromellose, titanium dioxide (E171),
propylene glycol, macrogol 6000 and purified talc.
What Metformin Tablets look like and contents of the pack
Metformin Tablets are white coloured, film coated round
biconvex tablets.
The tablets are supplied in blister packs of 28 and 84 tablets for
the 500mg dose and packs of 56 tablets for the 850mg dose.
Metformin Tablets are also available in securitainers of 500 tablets
for the 500mg dose and 300 tablets for the 850mg dose.
Marketing Authorisation Holder and Manufacturer
Relonchem Limited, 27, Old Gloucester Street, London, WC1 3XX.
Date leaflet last revised: September 2011
PL 20395/0027 and 0028

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Source: Medicines and Healthcare Products Regulatory Agency

Disclaimer: Every effort has been made to ensure that the information provided here is accurate, up-to-date and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. This information has been compiled for use by healthcare practitioners and consumers in the United States. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate that the drug or combination is safe, effective or appropriate for any given patient. If you have questions about the substances you are taking, check with your doctor, nurse or pharmacist.