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  • Diabetes medicine
  • Helps control blood sugar levels
  • Take with food
  • Avoid drinking alcohol while taking this medicine

About Metformin

Metformin is a type of diabetes medicine, a medicine used to help control blood sugar levels in people with type 2 diabetes. This type of diabetes is characterised by the insufficient production of insulin in the pancreas, or the insulin that the body makes does not work properly. This can lead to too high levels of glucose (sugar) in the blood and cause damage to blood vessels, nerves and organs.

Metformin helps lower blood sugar. It's usually prescribed for type 2 diabetes when diet and exercise alone have not been enough to control your blood sugar levels. Metformin is typically used in patients who are overweight or obese.

How to use Metformin

The guidelines for use are as follows:

  • Metformin tablets are swallowed whole with a drink of water, without chewing.
  • It's best to take Metformin tablets with your evening meal to reduce the chance of getting side effects such as stomach distress.
  • If you only take this medicine once a day, you should take your dose with breakfast.
  • If you need to take more than one dose a day, it is important to space the doses evenly throughout the day. For instance, with or just after each meal.


Dosage varies per person and is determined by a doctor for each specific patient depending on the symptoms. The general guidelines for use are listed below.

  • Children aged 10 and above: the usual starting dose is 500 mg or 850 mg Metformin once daily. The maximum daily dose is 2000 mg taken as two or three doses.

Treatment of children aged 10-12 years is only recommended on specific advice from your doctor, as experience in this age group is limited.

  • Adults: the usual starting dose is 500 mg or 850 mg of Metformin twice or three times daily. The maximum daily dose is 3000 mg taken in three doses.

If you are also taking insulin, your doctor will tell you how to start therapy with Metformin. Your doctor will need to take regular blood glucose tests and monitor your kidney function frequently.

Taken too much/forgot to take/stop taking Metformin

If you take more Metformin tablets than prescribed by your doctor, lactic acidosis may occur (see section ‘When should this medicine be used with caution’). If you experience any of the symptoms described in this section, you may need immediate hospital treatment because lactic acidosis can lead to coma.

If you forget to take a dose, do not take a double dose to make up for a forgotten tablet. Skip the missed dose and take the next tablet at the usual time.

Do not stop the treatment earlier than agreed without talking to your doctor.

When not to use Metformin

Metformin is not suitable for everyone. Do not take this medicine if:

  • You are allergic to metformin or any other ingredient in this medicine (see section ‘What Metformin contains’).
  • You have kidney or liver problems.
  • You have uncontrolled diabetes, with, for example, severe hyperglycaemia (high blood glucose), nausea, vomiting, diarrhoea, rapid weight loss or ketoacidosis.
  • You are dehydrated due to prolonged or severe diarrhoea or repeated vomiting. Dehydration can lead to kidney problems which can cause lactic acidosis.
  • You have a severe infection, such as an infection that affects the lungs. Severe infections can increase the risk of lactic acidosis.
  • You are being treated for heart failure or have recently had a heart attack, if you have serious circulatory problems (such as shock) or breathing problems. This can lead to a lack in oxygen supply to tissue, which can increase the risk of lactic acidosis.
  • You drink a lot of alcohol.

When should this medicine be used with caution?

The following warnings and precautions have been associated with the use of Metformin.

Risk of lactic acidosis

  • Consult a doctor if you need to have major surgery, or if you need to have an injection of a contrast medium that contains iodine into your bloodstream, for example in the context of an X-ray or scan, you must stop taking Metformin before and after the test or procedure. Your doctor will decide if you need to take another medicine during this time.
  • Metformin may cause a very rare, but very serious side effect called lactic acidosis, particularly if your kidneys are not working properly. The risk of developing lactic acidosis is also increased with uncontrolled diabetes, prolonged fasting or alcohol intake. Symptoms of lactic acidosis include vomiting, stomach ache with muscle cramps, a general feeling of not being well with severe tiredness, difficulty in breathing.

Stop taking Metformin and contact a doctor or the nearest hospital immediately if you experience some of the symptoms of lactic acidosis, as this condition may lead to coma.

Risk of low blood sugar (hypoglycaemia)

  • Be especially careful if you use Metformin with other antidiabetic agents (e.g., sulfonylureas, insulin, meglitinides), as this may cause hypoglycaemia. Symptoms of hypoglycaemia include weakness, dizziness, increased sweating, rapid pulse, visual disturbance and disorientation. Have a sugary drink or snack if your blood sugar is too low.


Avoid alcohol while taking Metformin since this may increase the risk of lactic acidosis, particulary if you have liver problems or are undernourished.

Do not drive if your blood sugar level is not stable. Blood sugar levels that are too low can affect your ability to react.

Pregnancy and breastfeeding

Tell your doctor if you are, or you think you may be, pregnant or are planning to become pregnant, so that your treatment can be adjusted.

Metformin is not suitable for use in breastfeeding women.

Other medicines and Metformin

Metformin is known to interact with other medicines, including:

  • ACE inhibitors.
  • Medicines which increase urine production (diuretics).
  • Bèta-2-agonists such as salbutamol or terbutaline.
  • Corticosteroids.
  • Other medicines to treat diabetes.

You may need more frequent blood glucose and kidney function tests, or your doctor may need to adjust your dose of Metformin.

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

Side effects

Medicines can cause side effects, although some people may not experience any. The side effects that are known to be associated with Metformin include:

Very common (may affect more than 1 in 10 users):

  • Gastrointestinal symptoms as nausea, vomiting, diarrhoea, abdominal pain and loss of appetite. These side effects occur most frequently at the beginning of the treatment with Metformin. It helps if you spread the doses over the day and if you take the Metformin tablets with a meal. If symptoms continue, stop taking Metformin and talk to your doctor.

Common (may affect less than 1 in 10 users):

  • Changes in taste sensations.

Very rare (may affect less than 1 in 10,000 users):

  • Lactic acidosis may occur (see section ‘When should this medicine be used with caution’). If this happens you must stop taking Metformin and contact a doctor or the nearest
  • hospital immediately, as lactic acidosis may lead to coma.
  • Skin reactions such as redness of the skin, itching or rash (hives).
  • Low vitamin B12 levels in the blood.
  • Abnormalities in liver function tests or liver inflammation (hepatitis). If this happens to you, you should stop taking this medicine and seek medical advice.

For more information on side effects, see the package leaflet. Consult your doctor or pharmacist if you experience these or other side effects.

What Metformin contains

The active substance is metformin hydrochloride.

Each tablet contains 500 mg, 850 mg or 1000 mg metformin hydrochloride.

The other ingredients are: povidone K90, magnesium stearate, hypromellose, macrogol.

The manufacturers of Metformin hydrochloride Mylan are:

Milpharm Limited Ares, Odyssey Business Park
West End Road
South Ruislip HA4 6QD
United Kingdom

APL Swift Services (Malta) Limited HF26, Hal Far Industrial Estate, Hal Far
Birzebbugia, BBG 3000

Package leaflet

Read the package leaflet before use.

Reviewed by:

Dr Wouter Mol, General practitioner Registrationnumber: BIG: 9057675501 Last checked: 08-12-2023 | Still valid

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