metformin hydrochloride


metformin hydrochloride

Consumer Medicine Information

What is in this leaflet

This leaflet answers some common questions about DIAFORMIN.

It does not contain all the available information. It does not take the place of talking to your doctor, diabetes educator or pharmacist.

All medicines have benefits and risks. Your doctor has weighed the risks of you taking DIAFORMIN against the benefits expected for you.

If you have any concerns about taking this medicine, talk to your doctor, pharmacist or diabetes educator.

Keep this leaflet with your medicine.

You may need to read it again.

What DIAFORMIN is used for

DIAFORMIN is used to control blood glucose (the amount of sugar in the blood) in people with diabetes mellitus.

DIAFORMIN can be used in type 2 diabetes in adults and children over 10 years of age. It is especially useful in those who are overweight, when diet and exercise are not enough to lower high blood glucose levels (hyperglycaemia). For adult patients, metformin can be used alone, or in combination with other oral diabetic medicines or in combination with insulin in insulin requiring type 2 diabetes.

Ask your doctor if you have any questions about why DIAFORMIN has been prescribed for you.

Your doctor may have prescribed DIAFORMIN for another reason.

DIAFORMIN is available only with a doctor's prescription.

There is no evidence that DIAFORMIN is addictive.


DIAFORMIN belongs to a group of medicines called biguanides. DIAFORMIN lowers high blood glucose (hyperglycaemia) by helping your body make better use of the insulin produced by your pancreas.

People with type 2 diabetes are unable to make enough insulin or their body does not respond properly to the insulin it does make. This causes a build up of glucose in the blood, which can lead to serious medical problems.

Long-term hyperglycaemia can lead to heart disease, blindness, kidney damage, poor blood circulation and gangrene.

Signs of hyperglycaemia may include:

tiredness or lack of energy



passing large amounts of urine

blurred vision.

Before you take DIAFORMIN

When you must not take it

Do not take DIAFORMIN if you are allergic to:

medicines containing metformin or any other biguanide

any of the ingredients listed at the end of this leaflet

Some of the symptoms of an allergic reaction may include skin rash, itching or hives; swelling of the face, lips or tongue which may cause difficulty in swallowing or breathing; wheezing or shortness of breath.

Do not take DIAFORMIN if you have any of the following conditions:

type 1 diabetes mellitus that is well controlled by insulin alone

type 2 diabetes that is already well controlled by diet alone

any type of metabolic acidosis such as lactic acidosis, diabetic ketoacidosis (a symptom of uncontrolled diabetes, in which substances called ketone bodies build up in the blood - you may notice this as an unusual fruity odour on your breath, difficulty breathing, confusion and frequent urination)

severe liver disease

excessive alcohol intake, binge drinking, alcohol dependence

kidney failure or severe kidney disease

dehydration, severe blood loss, shock

a severe infection

certain heart or blood vessel problems, including a recent heart attack or severe heart failure (when the heart fails to pump blood effectively)

severe breathing difficulties

blood clots in the lungs (symptoms include coughing, shortness of breath, chest pain and a fast heart rate)


inflammation of the pancreas (pancreatitis), symptoms include severe upper stomach pain, often with nausea and vomiting

Do not take DIAFORMIN if you need to have major surgery or an examination such as an X-ray or a scan requiring an injection of iodinated contrast (dye).

You must stop taking DIAFORMIN for a certain period of time before and after the examination or the surgery. Your doctor will decide whether you need any other treatment for this time. It is important that you follow your doctor's instructions precisely.

Do not take this medicine if you are pregnant or plan to become pregnant.

The safety of DIAFORMIN in pregnant women has not been established.

Insulin is more suitable for controlling blood glucose during pregnancy. Your doctor will replace DIAFORMIN with insulin while you are pregnant.

Do not take DIAFORMIN if you are breastfeeding.

DIAFORMIN is not recommended while you are breastfeeding. Your doctor will discuss the options available to you.

Do not take this medicine after the expiry date printed on the pack or if the packaging is torn or shows signs of tampering.

If it has expired or is damaged, return it to your pharmacist for disposal.

If you are not sure whether you should start taking DIAFORMIN, ask your doctor.

Before you start to take it

Tell your doctor if you have allergies to any other medicines, foods, dyes or preservatives.

Tell your doctor if you have or have had any of the following medical conditions:

heart failure

kidney problems.

Your doctor may want to take special care if you have any of these conditions.

Tell your doctor if you drink alcohol.

Alcohol can affect the control of your diabetes. Drinking excessive amounts of alcohol while you are being treated with DIAFORMIN may also lead to serious side effects. Your doctor may suggest you stop drinking or reduce the amount of alcohol you drink.

If you have not told your doctor about any of the above, tell him/her before you start taking DIAFORMIN.

Taking other medicines

Tell your doctor or pharmacist if you are taking any other medicines, including any that you buy without a prescription from a pharmacy, supermarket or health food shop.

Some medicines and DIAFORMIN may interact with each other. These include:

other medicines used to treat diabetes

medicines that contain alcohol, such as cough and cold syrups

tetracosactrin, a medicine used in people with multiple sclerosis, and in young children to treat some types of seizures (fits)

danazol, a medicine used to treat endometriosis

some medicines used to treat high blood pressure and some heart conditions, including beta blockers, calcium channel blockers and ACE inhibitors

medicines used to prevent blood clots such as warfarin

diuretics, also called fluid tablets

chlorpromazine, a medicine used to treat schizophrenia and other mental illnesses

NSAIDs (non-steroidal anti-inflammatory drugs), medicines used to relieve pain, swelling and other symptoms of inflammation, such as aspirin, diclofenac, ibuprofen, meloxicam, naproxen or piroxicam

cimetidine, a medicine commonly used to treat reflux and ulcers

corticosteroids such as prednisone or cortisone

some medicines used to treat asthma such as salbutamol or terbutaline

medicines that are substrates/ inhibitors of organic cation transporters - OCT 1 such as verapamil; OCT 2 such as dolutegravir, crizotinib, olaparib, daclatasvir or vandetanib

medicines that are inducers of OCT 1 such as rifampicin

medicines that may increase the risk of lactic acidosis when concomitantly used with metformin hydrochloride such as topiramate and other carbonic anhydrase inhibitors

These medicines may be affected by DIAFORMIN or may affect how well it works. You may need different amounts of your medicines or you may need to take different medicines.

Your doctor and pharmacist have more information on medicines to be careful with or avoid while taking this medicine.

How to take DIAFORMIN

Follow all directions given to you by your doctor and pharmacist carefully.

They may differ from the information contained in this leaflet.

If you do not understand the instructions on the pack, ask your doctor or pharmacist for help.

How much to take

The dose varies from person to person. Your doctor will decide the right dose for you.

The usual starting dose for adults is 500 mg one to two times a day. Your doctor may increase or decrease the dose, depending on your blood glucose levels. The maximum recommended dose is 1000 mg three times a day.

The elderly and people with kidney problems may need smaller doses.

Children & Adolescents:

The usual starting dose for children from 10 years of age and adolescents is one tablet of 500 mg or 850 mg once daily. Your doctor may increase or decrease the dose, depending on your blood glucose levels.

The maximum recommended dose is 2 g taken as two or three divided doses.

If your child has diabetes that is resistant to insulin and is being treated in hospital, your child's doctor will decide the dose.

How to take it

Swallow the tablets with a glass of water.

The 500 mg and 1000 mg tablets can be divided in half along the breakline, if advised by your doctor or pharmacist.

When to take it

Take DIAFORMIN during or immediately after food.

This will reduce the chance of a stomach upset.

Take your medicine at about the same time each day.

Taking it at the same time each day will have the best effect. It will also help you remember when to take it.

How long to take it for

Continue taking your medicine for as long as your doctor tells you to.

This medicine helps control diabetes but does not cure it. Most people will need to take DIAFORMIN on a long-term basis.

If you forget to take it

If it is almost time for your next dose, skip the dose you missed and take your next dose when you are meant to.

Otherwise, take the missed dose as soon as you remember (with food), and then go back to taking your tablets as you would normally.

Do not take a double dose to make up for the dose you missed.

If you are not sure what to do, ask your doctor or pharmacist.

If you take too much (overdose)

Immediately telephone your doctor or the Poisons Information Centre (telephone 13 11 26) for advice, or go to Accident and Emergency at the nearest hospital, if you think you or anyone else may have taken too much DIAFORMIN. Do this even if there are no signs of discomfort or poisoning.

If you take too much DIAFORMIN, you may feel sleepy, very tired, sick, vomit, have trouble breathing and have unusual muscle pain, stomach pain or diarrhoea. These may be early signs of a serious condition called lactic acidosis (build-up of lactic acid in the blood).

You may also experience symptoms of hypoglycaemia (low blood glucose). This usually only happens if you take too much DIAFORMIN together with other medicines for diabetes or with alcohol.

If you do experience any signs of hypoglycaemia, raise your blood glucose quickly by eating jelly beans, sugar or honey, drinking a non-diet soft drink or taking glucose tablets.

While you are taking DIAFORMIN

Things you must do

Make sure that you, your friends, family and work colleagues can recognise the symptoms of hypoglycaemia and hyperglycaemia and know how to treat them.


DIAFORMIN does not normally cause hypoglycaemia, although you may experience it if you take other medicines for diabetes such as sulfonylureas or repaglinide; or if you also use insulin.

Hypoglycaemia can occur suddenly. Initial signs may include:

weakness, trembling or shaking


light-headedness, dizziness, headache or lack of concentration

irritability, tearfulness or crying


numbness around the lips and tongue.

If not treated promptly, these may progress to:

loss of co-ordination

slurred speech


fits or loss of consciousness

If you experience any of the symptoms of hypoglycaemia, you need to raise your blood glucose immediately.

You can do this by doing one of the following:

eating 5 to 7 jelly beans

eating 3 teaspoons of sugar or honey

drinking half a can of non-diet soft drink

taking 2 to 3 concentrated glucose tablets

Unless you are within 10 to 15 minutes of your next meal or snack, follow up with extra carbohydrates such as plain biscuits, fruit or milk.

Taking this extra carbohydrate will prevent a second drop in your blood glucose level.


If you notice the return of any of the signs of hyperglycaemia, contact your doctor immediately.

Your doctor may need to consider additional or other treatments for your diabetes.

The risk of hyperglycaemia is increased in the following situations:

uncontrolled diabetes

illness, infection or stress

taking less DIAFORMIN than prescribed

taking certain other medicines

too little exercise

eating more carbohydrates than normal.

Tell your doctor if you:

become ill

become dehydrated

are injured

have a fever

have a serious infection

plan to have surgery (including dental surgery)

Your blood glucose may become difficult to control at these times. You may also be more at risk of developing a serious condition called lactic acidosis. At these times, your doctor may replace DIAFORMIN with insulin.

If you are about to be started on any new medicine, remind your doctor and pharmacist that you are taking DIAFORMIN.

Tell all the other doctors, dentists and pharmacists who treat you that you are taking this medicine.

If you become pregnant while taking DIAFORMIN, tell your doctor immediately.

Tell your doctor if any of the following happen:

you become ill

you become dehydrated (for instance due to persistent or severe diarrhoea or recurrent vomiting)

you are injured

you have a fever

you have a serious infection such an influenza, respiratory tract infection or urinary tract infection

you are having major surgery

you are having an examination such as an X-ray or a scan requiring an injection of an iodinated contrast agent (dye)

Your blood glucose may become difficult to control at these times. You may also be more at risk of developing a serious condition called lactic acidosis. At these times, your doctor may replace DIAFORMIN with insulin.

Visit your doctor regularly for check-ups.

Your doctor may want to perform blood tests to check your kidneys, liver, heart and vitamin B12 level while you are taking DIAFORMIN.

Check your blood glucose levels regularly.

This is the best way to tell if your diabetes is being controlled properly. Your doctor or diabetes educator will show you how and when to do this.

When you start treatment with DIAFORMIN, it can take up to two weeks for your blood glucose levels to be properly controlled.

Carefully follow the advice of your doctor and dietician on diet, drinking alcohol and exercise.

Things you must not do

Do not take DIAFORMIN to treat any other complaints unless your doctor tells you to.

Do not give your medicine to anyone else, even if they have the same condition as you.

Do not skip meals while taking DIAFORMIN.

Do not stop taking your medicine or change the dosage without checking with your doctor.

Things to be careful of

If you have to be alert, for example when driving, be especially careful not to let your blood glucose levels fall too low.

Low blood glucose levels may slow your reaction time and affect your ability to drive or operate machinery. Drinking alcohol can make this worse. However, DIAFORMIN by itself is unlikely to affect how you drive or operate machinery.

If you become sick with a cold, fever or flu, it is very important to continue eating your normal meals.

Your diabetes educator or dietician can give you a list of foods to eat on sick days.

When you are travelling, it is a good idea to:

wear some form of identification (e.g. bracelet) showing you have diabetes

carry some form of sugar to treat hypoglycaemia if it occurs, for example, sugar sachets or jelly beans

carry emergency food rations in case of a delay, for example, dried fruit, biscuits or muesli bars

bring enough DIAFORMIN tablets with you, so you don't miss any doses.

Lifestyle measures that help reduce heart disease risk

By following these simple measures, you can further reduce the risk from heart disease.

Quit smoking and avoid second-hand smoke

Limit alcohol intake

Enjoy healthy eating by:

eating plenty of vegetables and fruit;

reducing your saturated fat intake (eat less fatty meats, full fat dairy products, butter, coconut and palm oils, most take-away foods, commercially-baked products).

Be active. Progress, over time, to at least 30 minutes of moderate-intensity physical activity on 5 or more days each week. Can be accumulated in shorter bouts of 10 minutes duration. If you have been prescribed anti-angina medicine, carry it with you when being physically active

Maintain a healthy weight

Discuss your lifestyle and lifestyle plans with your doctor

For more information and tools to improve your heart health, call Heartline, the Heart Foundation's national telephone information service, on 1300 36 27 87 (local call cost)

Know warning signs of heart attack and what to do:

Tightness, fullness, pressure, squeezing, heaviness or pain in your chest, neck, jaw, throat, shoulders, arms or back

You may also have difficulty breathing, or have a cold sweat or feel dizzy or light headed or feel like vomiting (or actually vomit)

If you have heart attack warning signs that are severe, get worse or last for 10 minutes even if they are mild, call triple zero (000). Every minute counts.

Side effects

Tell your doctor or pharmacist as soon as possible if you do not feel well while you are taking DIAFORMIN.

DIAFORMIN helps most people with diabetes but it may have unwanted side effects in some people.

All medicines can have side effects. Sometimes they are serious, most of the time they are not. You may need medical attention if you get some of the side effects.

If you are over 65 years of age, you may have an increased chance of getting side effects.

Do not be alarmed by the following lists of side effects.

You may not experience any of them.

Ask your doctor or pharmacist to answer any questions you may have.

Tell your doctor or pharmacist if you notice any of the following and they worry you:

feeling sick (nausea)



stomach pain

taste disturbance

loss of appetite

skin reactions such as redness of the skin, itching or an itchy rash (urticaria)

These are generally mild side effects which disappear after the first few weeks. Taking DIAFORMIN with meals can help reduce stomach pain, nausea and diarrhoea. Skin reactions have been reported rarely.

Tell your doctor immediately or go to Accident and Emergency at the nearest hospital if you notice any of the following symptoms of lactic acidosis (build-up of lactic acid in the blood):

nausea, vomiting, stomach pain

trouble breathing

feeling weak, tired or generally unwell

unusual muscle pain


dizziness or light-headedness

shivering, feeling extremely cold

slow heart beat

Lactic acidosis is a very rare but serious side effect requiring urgent medical attention or hospitalisation. Although rare, if lactic acidosis does occur, it can be fatal. The risk of lactic acidosis is higher in the elderly, those whose diabetes is poorly controlled, those with prolonged fasting, those with certain heart conditions, those who drink alcohol and those with kidney or liver problems.

Tell your doctor or pharmacist if you notice anything that is making you feel unwell.

Other side effects not listed above may also occur in some people.

Some side effects (e.g. reduced vitamin B12 level) can only be found when your doctor does tests from time to time to check your progress.

After taking DIAFORMIN


Keep your tablets in the blister pack until it is time to take them.

If you take the tablets out of the blister pack they may not keep well.

Keep your tablets in a cool dry place where the temperature stays below 30°C.

Do not store DIAFORMIN or any other medicine in the bathroom or near a sink. Do not leave it in the car or on window sills.

Heat and dampness can destroy some medicines.

Keep it where children cannot reach it.

A locked cupboard at least one-and-a-half metres above the ground is a good place to store medicines.


If your doctor tells you to stop taking this medicine or the expiry date has passed, ask your pharmacist what to do with any medicine that is left over.

Product description

What it looks like

DIAFORMIN tablets are available in 3 strengths:

DIAFORMIN (500 mg) - 15.65 mm x 7.25 mm, oblong, white, clear coated, tablet debossed "MF/1" on one side and blank on the other.. Each pack contains 100 tablets.

DIAFORMIN 850 - 12.5 mm normal convex, white, clear film-coated tablet, debossed "MF" over "2" on one side and "G" on the other. Each pack contains 60 tablets.

DIAFORMIN 1000 - 19 mm x 10.5 mm, oval, film coated white tablet, debossed "MF/3" on one side and "G" on the other side. Each pack contains 90 tablets.


The tablets contain metformin hydrochloride as the active ingredient and are available in three strengths 500 mg, 850 mg and 1000 mg.

The tablets also contain:


magnesium stearate

OPADRY complete film coating system 20C59060 Clear (ARTG PI No: 106044).

DIAFORMIN contains trace quantities of sulfites.


DIAFORMIN is supplied in Australia by:

Alphapharm Pty Ltd trading as Viatris

Level 1, 30 The Bond

30-34 Hickson Road

Millers Point NSW 2000


Phone: 1800 274 276

This leaflet was prepared in

September 2022.

Australian registration numbers:

DIAFORMIN (500 mg) - AUST R 73806

DIAFORMIN 850 - AUST R 73808

DIAFORMIN 1000 - AUST R 82207

DIAFORMIN is also available as bulk pack for dose administration to aid packers:

DIAFORMIN (500 mg) - AUST R 299825

DIAFORMIN 1000 - AUST R 294057

DIAFORMIN® is a Viatris company trade mark


Sponsored and funded by

GuildLink logo

GuildLink Pty Ltd
ABN 83 090 249 960
P.O. Box A284, South Sydney NSW 1235 Australia