Pharmacy Guide

Patient leaflets and SmPCs, drug interaction checker, official dosages and NHS pharmacy opening hours — all in one place.

Pharmacy Guide

Patient leaflets and SmPCs, drug interaction checker, official dosages and NHS pharmacy opening hours — all in one place.

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Metformin 850mg

⚠ This medicine appears to have been discontinued

The electronic medicines compendium (emc) no longer publishes a Summary of Product Characteristics for this product, which usually means it is no longer marketed in the UK. The patient leaflet below is kept for reference, but the product may not be available.

If you were prescribed this medicine, other products containing Metformin hydrochloride may still be available. Do not stop your treatment — ask your pharmacist or GP what to use instead.

Active substance: Metformin hydrochloride
Source: electronic medicines compendium (emc)
Official leaflet: Read the PIL on emc

What it is and what it is used for

for Metformin film-coated tablets contains metformin, a medicine to treat diabetes. It belongs to a group of medicines called biguanides. Metformin film-coated tablets is used to treat patients with type 2 diabetes (also called 'non-insulin dependent diabetes') when diet and exercise alone have not been enough to control your blood glucose levels. It is used particularly in overweight patients. Insulin is a hormone produced by the pancreas that makes your body take in glucose (sugar) from the blood. Your body uses glucose to produce energy or stores it for future use. If you have diabetes, your pancreas does not make enough insulin or your body is not able to use properly the insulin it produces. This leads to a high level of glucose in your blood. Metformin film-coated tablets helps to lower your blood glucose to as normal a level as possible. If you are an overweight adult, taking this medicine over a long period of time also helps to lower the risk of complications associated with diabetes. Metformin film-coated tablets is associated with either a stable body weight or modest weight loss. Adults can take metformin film-coated tablets on its own or together with other medicines to treat diabetes (medicines taken by mouth or insulin). Children 10 years and over and adolescents can take metformin film-coated tablets on its own or together with insulin.

What you need to know before you take it

e Metformin film-coated tablets Do not take Metformin film-coated tablets :

  • if you are allergic to metformin or any of the other ingredients of this medicine (listed in section 6).
  • if you have liver problems.
  • if you have severely reduced kidney function.

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•

•

•

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if you have uncontrolled diabetes, with, for example, severe hyperglycaemia (high blood glucose), nausea, vomiting, diarrhoea, rapid weight loss, lactic acidosis (see "Risk of lactic acidosis" below) or ketoacidosis. Ketoacidosis is a condition in which substances called 'ketone bodies' accumulate in the blood and which can lead to diabetic pre-coma. Symptoms include stomach pain, fast and deep breathing, sleepiness or your breath developing an unusual fruity smell. if you lost too much water from your body (dehydration), due to long-lasting or severe diarrhoea, or if you have vomited several times in a row. Dehydration may lead to kidney problems, which can put you at risk for lactic acidosis (see 'Warnings and precautions'). if you have a severe infection, such as an infection affecting your lungs or bronchial system or your kidney. Severe infections may lead to kidney problems, which can put you at risk for lactic acidosis (see 'Warnings and precautions'). if you are treated for acute heart failure or have recently had a heart attack, have severe problems with your circulation (such as shock) or have breathing difficulties. This may lead to a lack in oxygen supply to tissue which can put you at risk for lactic acidosis (see 'Warnings and precautions'). if you drink a lot of alcohol.

If any of the above applies to you, talk to your doctor before you start taking this medicine. Make sure you ask your doctor for advice if:

  • you need to have an examination such as X-ray or scan involving the injection of contrast medicines that contain iodine into your bloodstream.
  • you need to have major surgery. You must stop taking this medicine for a certain period of time before and after the examination or the surgery. Your doctor will decide whether you need any other treatment during this time. It is important that you follow your doctor's instructions precisely. Warnings and precautions Talk to your doctor or pharmacist before taking Metformin film-coated tablets. Risk of lactic acidosis Metformin film-coated tablets 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, serious infections, prolonged fasting or alcohol intake, dehydration, liver problems and any medical conditions in which a part of the body has a reduced supply of oxygen (such as acute severe heart disease). Talk to your doctor promptly for further instructions if:. –

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You are known to suffer from a genetically inherited disease affecting mitochondria (the energyproducing components within cells) such as MELAS syndrome (Mitochondrial Encephalopathy, myopathy, Lactic acidosis and Stroke-like episodes) or Maternal inherited diabetes and deafness (MIDD). You have any of these symptoms after starting metformin: seizure, declined cognitive abilities, difficulty with body movements, symptoms indicating nerve damage (e.g. pain or numbness), migraine and deafness

Stop taking Metformin film-coated tablets for a short time if you have a condition that may be associated with dehydration (significant loss of body fluids) such as severe vomiting, diarrhoea, fever, exposure to heat or if you drink less fluid than normal. Talk to your doctor for further instructions. Stop taking Metformin film-coated tablets 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.

Symptoms of lactic acidosis include:

  • vomiting
  • stomach ache (abdominal pain)
  • muscle cramps
  • a general feeling of not being well with severe tiredness
  • difficulty in breathing
  • reduced body temperature and heartbeat. Lactic acidosis is a medical emergency and must be treated in a hospital. If you need to have major surgery you must stop taking this medicine during and for some time after the procedure. Your doctor will decide when you must stop and when to restart your treatment with Metformin film-coated tablets . Metformin film-coated tablets on its own does not cause hypoglycaemia (a blood glucose level which is too low). However, if you take Metformin film-coated tablets together with other medicines to treat diabetes (such as sulphonylureas, insulin or meglitinides) there is a risk of hypoglycaemia. If you experience symptoms of hypoglycaemia such as weakness, dizziness, increased sweating, fast heart beating, vision disorders or difficulty in concentration, it usually helps to eat or drink something containing sugar. During treatment with this medicine, your doctor will check your kidney function at least once a year or more frequently if you are elderly and/or if you have worsening kidney function. Children and adolescents Treatment of children between 10 and 12 years of age is only recommended on specific advice from your doctor, as experience in this age group is limited (see section 3 "Use in children and adolescents"). Other medicines and Metformin film-coated tablets Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines. You may need more frequent blood glucose and kidney function tests or your doctor may need to adjust the dosage of Metformin film-coated tablets. 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 film-coated tablets before or at the time of injection. Your doctor will decide when you must stop and when to restart your treatment with Metformin film-coated tablets . It is especially important to mention to your doctor if you are taking:
  • medicines which increase urine production (diuretics).
  • medicines used to treat pain and inflammation (NSAID and COX-2-inhibitors, such as ibuprofen and celecoxib).
  • certain medicines for the treatment of high blood pressure (ACE inhibitors and angiotensin II receptor antagonists).
  • beta-2 agonists such as salbutamol or terbutaline (used to treat asthma).
  • corticosteroids (used to treat a variety of conditions, such as severe inflammation of the skin or in asthma).
  • medicines that may change the amount of metformin in your blood, especially if you have reduced kidney function (such asverapamil, rifampicin, cimetidine, dolutegravir, ranolazine, trimethoprime, vandetanib, isavuconazole, crizotinib, olaparib).
  • other medicines used to treat diabetes. Metformin film-coated tablets with alcohol

Avoid excessive alcohol intake while taking Metformin film-coated tablets since this may increase the risk of lactic acidosis (see section 'Warnings and precautions'). Pregnancy and breast-feeding If you are pregnant, think you may be pregnant or are planning to have a baby, speak to your doctor in case any changes will be needed to your treatment or monitoring of your blood glucose levels. This medicine is not recommended if you are breast-feeding or if you are planning to breast-feed your baby. Driving and using machines Metformin film-coated tablets on its own does not cause hypoglycaemia (a blood glucose level which is too low). This means that it will not affect your ability to drive or use machines. However, take special care if you take Metformin film-coated tablets together with other medicines to treat diabetes that can cause hypoglycaemia (such as sulphonylureas, insulin, meglitinides). Symptoms of hypoglycaemia include weakness, dizziness, increased sweating, fast heartbeat, vision disorders or difficulty in concentration. Do not drive or use machines if you start to feel these symptoms.

How to take it

Metformin film-coated tablets Always take this medicine exactly as your doctor or pharmacist has told you. Check with your doctor or pharmacist if you are not sure. Metformin film-coated tablets cannot replace the benefits of a healthy lifestyle. Continue to follow any advice about diet that your doctor has given you and get some regular exercise. The recommended dose is: Adults usually start with 500 mg or 850 mg Metformin film-coated tablets two or three times a day. The maximum daily dose is 3000 mg taken as 3 divided doses. If you have reduced kidney function, your doctor may prescribe a lower dose. If you take insulin too, your doctor will tell you how to take Metformin film-coated tablets . Use in children and adolescents Children 10 years and over and adolescents usually start with 500 mg or 850 mg Metformin film-coated tablets once a day. The maximum daily dose is 2000 mg taken as 2 or 3 divided doses. Treatment of children between 10 and 12 years of age is only recommended on specific advice from your doctor, as experience in this age group is limited. Monitoring

  • Your doctor will perform regular blood glucose tests and will adapt your dose of metformin to your blood glucose levels. Make sure that you talk to your doctor regularly. This is particularly important for children and adolescents or if you are an older person.
  • Your doctor will also check at least once a year how well your kidneys work. You may need more frequent checks if you are an older person or if your kidneys are not working normally. Taking Metformin film-coated tablets: Take this medicine during or after a meal. This will avoid you having side effects affecting your digestion. Do not crush or chew the tablets. Swallow each tablet with a glass of water.
  • If you take one dose a day, take it in the morning (breakfast).
  • If you take two divided doses a day, take them in the morning (breakfast) and evening (dinner).
  • If you take three divided doses a day, take them in the morning (breakfast), at noon (lunch) and in the evening (dinner).

If, after some time, you think that the effect of this medicine is too strong or too weak, talk to your doctor or pharmacist. If you take more Metformin film-coated tablets than you should If you have taken more medicine than you should have, you may experience lactic acidosis. Symptoms of lactic acidosis are non-specific such as vomiting, bellyache (abdominal pain) with muscle cramps, a general feeling of not being well with severe tiredness and difficulty in breathing. Further symptoms are reduced body temperature and heartbeat. If you experience some of these symptoms, you should seek immediately medical attention, as lactic acidosis may lead to coma. Stop taking Metformin film-coated tablets immediately and contact a doctor or the nearest hospital straight away. If you forget to take Metformin film-coated tablets Do not take a double dose to make up for a forgotten dose. Take the next dose at the usual time. If you have any further questions on the use of this medicine, ask your doctor or pharmacist.

Possible side effects

Like all medicines, this medicine can cause side effects, although not everybody gets them. Metformin film-coated tablets may cause a very rare (may affect up to 1 in 10,000 people), but very serious side effect called lactic acidosis (see section 'Warnings and precautions'). If this happens you must stop taking Metformin film-coated tablets and contact a doctor or the nearest hospital immediately, as lactic acidosis may lead to coma. Other side effects which may occur: Very common (may affect more than 1 in 10 people)

  • digestive problems such as feeling sick (nausea), being sick (vomiting), diarrhoea, bellyache (abdominal pain) and loss of appetite. These side effects most often happen at the beginning of the treatment with metformin film coated tablets. It helps if you spread the doses over the day and if you take this medicine with or straight after a meal. If symptoms continue, stop taking Metformin film-coated tablets and talk to your doctor. Common (may affect up to 1 in 10 people)
  • changes in taste.
  • decreased or low vitamin B12 levels in the blood (symptoms may include extreme tiredness (fatigue), a sore and red tongue (glossitis), pins and needles (paraesthesia) or pale or yellow skin). Your doctor may arrange some tests to find out the cause of your symptoms because some of these may also be caused by diabetes or due to other unrelated health problems. Very rare (may affect up to 1 in 10,000 people)
  • lactic acidosis. This is a very rare but serious complication particularly if your kidneys are not working properly. Symptoms of lactic acidosis are non-specific (see section 'Warning and precautions').
  • abnormalities in liver function tests or hepatitis (inflammation of the liver; this may cause tiredness, loss of appetite, weight loss, with or without yellowing of the skin or whites of the eyes). If this happens to you, stop taking Metformin film-coated tablets and talk to your doctor.
  • skin reactions such as redness of the skin (erythema), itching or an itchy rash (hives). Additional side effects in children and adolescents

Limited data in children and adolescents showed that adverse events were similar in nature and severity to those reported in adults. Reporting of side effects If you get any side effects, talk to your doctor or pharmacist. 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.

How to store it

Metformin film-coated tablets Keep this medicine out of the sight and reach of children. If a child is treated with Metformin film-coated tablets, parents and caregivers are advised to oversee how this medicine is taken.This medicine does not require any special storage conditions. Do not use this medicine after the expiry date which is stated on the carton or the bottle or the blister after 'EXP'. The expiry date refers to the last day of that month.Do not throw any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help to protect the environment.

Contents of the pack and other information

What Metformin film-coated tablets contains The active substance is metformin hydrochloride. One film-coated tablet of Metformin 500 mg contains 500 mg metformin hydrochloride corresponding to 390 mg metformin base. One film-coated tablet of Metformin 850 mg contains 850 mg metformin hydrochloride corresponding to 662.9 mg metformin base. One film-coated tablet of Metformin 1000 mg contains 1000 mg metformin hydrochloride corresponding to 780 mg metformin base .

  • The other ingredients are: Sodium Starch Glycolate (Type A), povidone K-30, Maize Starch, Colloidal Anhydrous Silica, Magnesium stearate, Isopropyl alcohol, hypromellose, Titanium dioxide E171, Purified Talc, Macrogol – 6000, Propylene glycol. What Metformin film-coated tablets looks like and contents of the pack Metformin 500 mg film-coated tablets are white, round 11.00 mm, biconvex film-coated tablets debossed with '500' on one face and plain on the other. Metformin 850 mg film-coated tablets are white, round 13.50 mm, biconvex film-coated tablets debossed with '850' on one face and plain on the other. Metformin 1000 mg film-coated tablets are white to off-white oval shaped 19.00 mm x 10.50 mm , biconvex, film-coated tablets debossed with '10' and 00 on either side of deep notch on one side and breakline on the other side. Metformin 500 mg film-coated tablets are supplied in Clear PVC/PVDC/Aluminium blister of 14 tablets. Pack size: 14, 28, 56 or 84 tablets. Metformin 500 mg film-coated tablets are supplied in HDPE bottle. Pack size: 100, 105, 112, 336, 400 and 1000 tablets. Metformin 850 mg film-coated tablets are supplied in Clear PVC/PVDC/Aluminium blister of 14 tablets. Pack size: 14, 28, 56 or 84 tablets.

Metformin 850 mg film-coated tablets are supplied in HDPE bottle. Pack size: 250 and 500 tablets. Metformin 1000 mg film-coated tablets are supplied in Clear PVC/PVDC/Aluminium blister of 14 tablets. Pack size: 14, 28, 56 or 84 tablets. Metformin 1000 mg film-coated tablets are supplied in HDPE bottle. Pack size: 30, 63, 210 and 1000 tablets. Not all pack sizes may be marketed. Marketing Authorisation Holder and Manufacturer Ipca Laboratories UK Ltd., Unit 97-98, Silverbriar, Sunderland Enterprise Park East, Sunderland, SR5 2TQ, United Kingdom Telephone: +44 (0) 1915166517 Fax: +44 (0) 1915166526 Email: [email protected] Manufacturer: Elara Pharmaservices Limited Iron Farm, 7 Grimes Gates, Diseworth, DE74 2QD, United Kingdom This leaflet was last approved in 03/2025

Frequently asked questions about Metformin 850mg

What is the active substance in Metformin 850mg?

The active substance in Metformin 850mg is metformin hydrochloride.

Where does this information come from?

This leaflet reproduces the patient information leaflet approved for Metformin 850mg, as published on the electronic medicines compendium (emc). The version printed inside your medicine’s packaging is the one that applies to you.

Can I get Metformin 850mg without a prescription?

Whether a medicine is available over the counter or on prescription only depends on its licence. Check the leaflet, or ask your pharmacist — they can tell you straight away.

About this leaflet

The text above reproduces the patient information leaflet approved for this medicine, restructured for easier reading.

Medical disclaimer: This page is for information only and does not replace advice from your doctor or pharmacist. Always read the leaflet supplied with your medicine. If you are unwell, call NHS 111; in an emergency, call 999.

Medicines with the same active substance: Metformin hydrochloride (80 medicines)
See every medicine containing this substance, or browse the full A–Z of active substances.
⚕For healthcare professionals — Summary of Product Characteristics (SmPC)Full SmPC: dosage, interactions, contraindications, warnings+
Technical information intended for healthcare professionals (doctors and pharmacists). The Summary of Product Characteristics (SmPC) is the official document approved by the MHRA/EMA. It does not replace the patient leaflet or a doctor’s advice.

4.1. Therapeutic indications

Treatment of type 2 diabetes mellitus, particularly in overweight patients, when dietary management and exercise alone does not result in adequate glycaemic control.

• In adults, Metformin may be used as monotherapy or in combination with other oral antidiabetic agents or with insulin.

• In children from 10 years of age and adolescents, Metformin may be used as monotherapy or in combination with insulin.

A reduction of diabetic complications has been shown in overweight type 2 diabetic adult patients treated with metformin as first-line therapy after diet failure (see section 5.1).

4.2. Posology and method of administration

Posology

Adults with normal renal function (GFR≥ 90 mL/min)

Monotherapy and combination with other oral antidiabetic agents:

Metformin 500 mg film-coated tablets and Metformin 850 mg film-coated tablets

The usual starting dose is 500 mg or 850 mg metformin hydrochloride 2 or 3 times daily given during or after meals. After 10 to 15 days the dose should be adjusted on the basis of blood glucose measurements. A slow increase of dose may improve gastrointestinal tolerability.

The maximum recommended dose of metformin hydrochloride is 3 g daily, taken as 3 divided doses.

Metformin 1000 mg film-coated tablets

For patients taking high doses of metformin hydrochloride (2 to 3 g daily), two Metformin 500 mg tablets may be replaced with Metformin 1000 mg film-coated tablets. The maximum recommended daily dose is 3 g metformin hydrochloride divided into 3 daily doses.

If transfer from another oral antidiabetic agent is intended: discontinue the other agent and initiate metformin at the dose indicated above.

Combination with insulin:

Metformin and insulin may be used in combination therapy to achieve better blood glucose control. Metformin hydrochloride is given at the usual starting dose of 500 mg or 850 mg 2 or 3 times daily, while insulin dosage is adjusted on the basis of blood glucose measurements.

Elderly:

Due to the potential for decreased renal function in elderly subjects, the metformin dosage should be adjusted based on renal function. Regular assessment of renal function is necessary (see section 4.4).

Renal impairment:

GFR should be assessed before treatment with metformin-containing medicinal products begins and at least every year thereafter. In patients with increased risk of further impairment of renal function and in elderly, renal function should be assessed more often, eg. every 3-6 months.

GFRml/min

Total maximum daily dose(to be divided into 2-3 doses daily)

To consider

60-89

3000 mg

Dose reduction may be considered in relation to declining renal function.

45-59

2000 mg

Factors that may increase the risk of lactate acidosis (see section 4.4) should be–reviewd before considering initiation of metformin.The starting dose is at most half of the maximum dose.

30-44

1000 mg

< 30

-

Metformin is contraindicated.

Children and adolescents:

Paediatric population

Monotherapy and combination with insulin

• Metformin can be used in children from 10 years of age and adolescents.

• The usual starting dose is 500 mg or 850 mg metformin hydrochloride once daily, given during or after meals.

After 10 to 15 days the dose should be adjusted on the basis of blood glucose measurements. A slow increase of dose may improve gastrointestinal tolerability. The maximum recommended dose of metformin hydrochloride is 2 g daily, taken as 2 or 3 divided doses.

4.3. Contraindications

• Hypersensitivity to metformin or to any of the excipients listed in section 6.1.

• Any type of acute metabolic acidosis (such as lactic acidosis, diabetic ketoacidosis).

• Diabetic pre-coma.

• Sever renal failure ( GFR < 30 ml/min).

• Acute conditions with the potential to alter renal function such as: dehydration, severe infection, shock.

• Disease which may cause tissue hypoxia (especially acute disease, or worsening of chronic disease) such as: decompensated heart failure, respiratory failure, recent myocardial infarction, shock.

• Hepatic insufficiency, acute alcohol intoxication, alcoholism.

4.4. Special warnings and precautions for use

Lactic acidosis:

Lactic acidosis is a very rare, but serious (high mortality in the absence of prompt treatment), metabolic complication most often occurs at acute worsening of renal function or cardiorespiratory illness or sepsis.Metformin accumulation occurs at acute worsening of renal function and increases the risk of lactic acidosis.

In case of dehydration (severe diarrhoea or vomiting, fever or reduced fluid intake), metformin should be temporarily discontinued and contact with a health care professional is recommended.

Medicinal products that can acutely impair renal function (such as antihypertensives, diuretics and NSAIDs) should be initiated with caution in metformin-treated patients. Other risk factors for lactic acidosis are excessive alcohol intake; hepatic insufficiency, inadequately controlled diabetes, ketosis, prolonged fasting and any condition associated with hypoxia as well as concomitant use of medicinal products that may cause lactic acidosis (see sections 4.3 and 4.5).

Patients and/or care-givers should be informed of the risk of lactic acidosis. Lactic acidosis is characterised by acidotic dyspnoea muscle cramps, abdominal pain, asthenia, and hypothermia followed by coma. In case of suspected symptoms, the patient should stop taking metformin and seek immediate medical attention. Diagnostic laboratory findings are decreased blood pH (< 7.35), increased plasma lactate levels (5 mmol/l), and an increased anion gap and lactate/pyruvate ratio.

Patients with known or suspected mitochondrial diseases:

In patients with known mitochondrial diseases such as Mitochondrial Encephalopathy with Lactic Acidosis, and Stroke-like episodes (MELAS) syndrome and Maternal inherited diabetes and deafness (MIDD), metformin is not recommended due to the risk of lactic acidosis exacerbation and neurologic complications which may lead to worsening of the disease.

In case of signs and symptoms suggestive of MELAS syndrome or MIDD after the intake of metformin, treatment with metformin should be withdrawn immediately and prompt diagnostic evaluation should be performed.

Renal function:

GFR should be assessed before treatment initiation and regularly thereafter, see section 4.2 Metformin is contraindicated in patients with GFR <30 ml / min and should be temporarily discontinued in presence of conditions that alter renal function, see section 4.3.

Cardiac function

Patients with heart failure are more at risk of hypoxia and renal insufficiency. In patients with chronic stable heart failure, metformin may be used with regular monitoring of cardiac and renal function.

For patients with acute and unstable heart failure, metformin is contraindicated (see section 4.3).

Administration of iodinated contrast media:

Intravascular administration of iodinated contrast agents may lead to contrast-induced nephropathy resulting in metformin accumulation and increased risk of lactate acidosis. Metformin should be discontinued before or at the time of imaging procedure and should not be reinstated until at least 48 hours after, provided that renal function has been evaluated and demonstrated to be stable (see section 4.2 and 4.5).

Surgery:

Metformin must be discontinued at the time of surgery under general, spinal or epidural anaesthesia. Therapy may be restarted no earlier than 48 hours following surgery or resumption of oral nutrition and provided that renal function has been re-evaluated and found to be stable.

Paediatric population:

The diagnosis of type 2 diabetes mellitus should be confirmed before treatment with metformin is initiated.

No effect of metformin on growth and puberty has been detected during controlled clinical studies of one-year duration but no long-term data on these specific points are available. Therefore, a careful follow-up of the effect of metformin on these parameters in metformin-treated children, especially prepubescent children, is recommended.

Children aged between 10 and 12 years:

Only 15 subjects aged between 10 and 12 years were included in the controlled clinical studies conducted in children and adolescents. Although efficacy and safety of metformin in these children did not differ from efficacy and safety in older children and adolescents, particular caution is recommended when prescribing to children aged between 10 and 12 years.

Other precautions:

All patients should continue their diet with a regular distribution of carbohydrate intake during the day. Overweight patients should continue their energy-restricted diet.

The usual laboratory tests for diabetes monitoring should be performed regularly.

Metformin alone does not cause hypoglycaemia, but caution is advised when it is used in combination with insulin or other oral antidiabetics (e.g. sulfonylureas or meglitinides).

Metformin may reduce vitamin B12 serum levels. The risk of low vitamin B12 levels increases with increasing metformin dose, treatment duration, and/or in patients with risk factors known to cause vitamin B12 deficiency. In case of suspicion of vitamin B12 deficiency (such as anaemia or neuropathy), vitamin B12 serum levels should be monitored. Periodic vitamin B12 monitoring could be necessary in patients with risk factors for vitamin B12 deficiency. Metformin therapy should be continued for as long as it is tolerated and not contra-indicated and appropriate corrective treatment for vitamin B12 deficiency provided in line with current clinical guidelines.

4.5. Interaction with other medicinal products and other forms of interaction

Concomitant use not recommended:

Alcohol:

Alcohol intoxication is associated with an increased risk of lactic acidosis, particularly in case of fasting malnutrition or hepatic impairment.

Iodinated contrast agents

Metformin must be discontinued prior to, or at the time of the test and not be restarted until at least 48 hours after, provided that renal function has been re-evaluated and found to be stable (see section 4.2 and 4.4).

Combinations requiring precautions for use:

Some medicinal products can adversely affect renal function which may increase the risk of lactic acidosis, e.g. NSAIDs, including selective cyclo-oxygenase (COX) II inhibitors, ACE inhibitors, angiotensin II receptor antagonists and diuretics, especially loop diuretics. When starting or using such products in combination with metformin, close monitoring of renal function is necessary.

Medicinal products with intrinsic hyperglycaemic activity (e.g. glucocorticoids (systemic and local routes) and sympathomimetics):

More frequent blood glucose monitoring may be required, especially at the beginning of treatment. If necessary, adjust the metformin dosage during therapy with the respective medicinal product and upon its discontinuation.

Organic cation transporters (OCT)

Metformin is a substrate of both transporters OCT1 and OCT2.

Co-administration of metformin with

• Inhibitors of OCT1 (such as verapamil) may reduce efficacy of metformin.

• Inducers of OCT1 (such as rifampicin) may increase gastrointestinal absorption and efficacy of metformin.

• Inhibitors of OCT2 (such as cimetidine, dolutegravir, ranolazine, trimethoprime, vandetanib, isavuconazole) may decrease the renal elimination of metformin and thus lead to an increase in metformin plasma concentration.

• Inhibitors of both OCT1 and OCT2 (such as crizotinib, olaparib) may alter efficacy and renal elimination of metformin.

Caution is therefore advised, especially in patients with renal impairment, when these drugs are co-administered with metformin, as metformin plasma concentration may increase. If needed, dose adjustment of metformin may be considered as OCT inhibitors/inducers may alter the efficacy of metformin.

4.6. Fertility, pregnancy and lactation

Pregnancy

Uncontrolled hyperglycaemia in the periconceptional phase and during pregnancy is associated with increased risk of congenital abnormalities, pregnancy loss, pregnancy-induced hypertension, preeclampsia and perinatal mortality. It is important to maintain blood glucose levels as close to normal as possible throughout pregnancy, to reduce the risk of adverse hyperglycaemia-related outcomes to the mother and her child.

Metformin crosses the placenta with levels that can be as high as maternal concentrations.

A large amount of data on pregnant women (more than 1000 exposed outcomes) from a register-based cohort study and published data (meta-analyses, clinical studies, and registries) indicates no increased risk of congenital abnormalities nor feto/neonatal toxicity after exposure to metformin in the periconceptional phase and/or during pregnancy.

There is limited and inconclusive evidence on the metformin effect on the long-term weight outcome of children exposed in utero.Metformin does not appear to affect motor and social development up to 4 years of age in children exposed during pregnancy although data on long term outcomes are limited.

If clinically needed, the use of metformin can be considered during pregnancy and in the periconceptional phase as an addition or an alternative to insulin

Breast-feeding

Metformin is excreted into human breast milk. No adverse effects were observed in breastfed newborns/infants. However, as only limited data are available, breast-feeding is not recommended during metformin treatment. A decision on whether to discontinue breast-feeding should be made, taking into account the benefit of breast-feeding and the potential risk to adverse effects on the child.

Fertility

Fertility of male or female rats was unaffected by metformin when administered at doses as high as 600 mg/kg/day, which is approximately three times the maximum recommended human daily dose based on body surface area comparisons.

4.7. Effects on ability to drive and use machines

Metformin monotherapy does not cause hypoglycaemia and therefore has no effect on the ability to drive or to use machines.

However, patients should be alerted to the risk of hypoglycaemia when metformin is used in combination with other antidiabetic agents (e.g. sulfonylureas, insulin or meglitinides).

4.8. Undesirable effects

During treatment initiation, the most common adverse reactions are nausea, vomiting, diarrhoea, abdominal pain and loss of appetite which resolve spontaneously in most cases. To prevent them, it is recommended to take metformin in 2 or 3 daily doses and to increase slowly the doses.

The following adverse reactions may occur under treatment with metformin. Frequencies are defined as follows:

very common: ≥1/10; common ≥1/100, <1/10; uncommon ≥1/1,000, <1/100; rare ≥1/10,000, <1/1,000; very rare <1/10,000.

Within each frequency grouping, adverse reactions are presented in order of decreasing seriousness.

Metabolism and nutrition disorders:

Very rare:

Lactic acidosis (see section 4.4).

Common:

Vitamin B12 decrease/deficiency (see section 4.4).

Nervous system disorders:

Common: Taste disturbance

Gastrointestinal disorders:

Very common: Gastrointestinal disorders such as nausea, vomiting, diarrhoea, abdominal pain and loss of appetite. These undesirable effects occur most frequently during initiation of therapy and resolve spontaneously in most cases. To prevent them, it is recommended that metformin be taken in 2 or 3 daily doses during or after meals. A slow increase of the dose may also improve gastrointestinal tolerability.

Hepatobiliary disorders:

Very rare: Isolated reports of liver function tests abnormalities or hepatitis resolving upon metformin discontinuation.

Skin and subcutaneous tissue disorders:

Very rare: Skin reactions such as erythema, pruritus, urticaria

Paediatric population

In published and post marketing data and in controlled clinical studies in a limited paediatric population aged 10-16 years treated during 1 year, adverse event reporting was similar in nature and severity to that reported in adults.

Reporting of suspected adverse reactions

Reporting of suspected adverse reactions after approval is of great importance. It allows continuous monitoring of the benefit-risk balance of the drug. Healthcare professionals are asked to report any suspected adverse reactions 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

4.9. Overdose

Hypoglycaemia has not been seen with metformin hydrochloride doses of up to 85 g, although lactic acidosis has occurred in such circumstances. High overdose of metformin or concomitant risks may lead to lactic acidosis. Lactic acidosis is a medical emergency and must be treated in hospital. The most effective method to remove lactate and metformin is haemodialysis.

🇷🇴 Known in Romania as

Medicines sold in Romania with the same active substance: Cunoscut în România ca

⚠ Same active substance, but a different pharmaceutical form (for example a gel instead of a tablet). Not interchangeable — ask a pharmacist.

  • GLUCOPHAGE 500 mg prescriptionMETFORMINUM · taken by mouth
  • METFORMIN AUROBINDO 1000 mg prescriptionMETFORMINUM · taken by mouth
  • GLUCOPHAGE 850 mg prescriptionMETFORMINUM · taken by mouth
  • GLUCOPHAGE 1000 mg prescriptionMETFORMINUM · taken by mouth
  • BROTMIN 850 mg prescriptionMETFORMINUM · taken by mouth
  • BROTMIN 1000 mg prescriptionMETFORMINUM · taken by mouth

Same active substance. The strength, the form and whether you need a prescription can differ. Always ask a pharmacist before you switch. Romanian medicines in the UK →

🇵🇱 Known in Poland as

Medicines sold in Poland with the same active substance: W Polsce znany jako

⚠ Same active substance, but a different pharmaceutical form (for example a gel instead of a tablet). Not interchangeable — ask a pharmacist.

  • Metformax 500Metformini hydrochloridum · taken by mouth
  • Metformax 850Metformini hydrochloridum · taken by mouth
  • Siofor 500Metformini hydrochloridum · taken by mouth
  • Siofor 850Metformini hydrochloridum · taken by mouth
  • Siofor 1000Metformini hydrochloridum · taken by mouth
  • Glucophage XRMetformini hydrochloridum · taken by mouth

Same active substance. The strength, the form and whether you need a prescription can differ. Always ask a pharmacist before you switch. Polish medicines in the UK →

💬 Ask about this leaflet

Ask anything about Metformin 850mg. The assistant answers only from this leaflet — if the leaflet does not cover it, it will say so. It does not give medical advice.

Answers come from the patient leaflet published on the electronic medicines compendium (emc). They are not medical advice. Ask a pharmacist or your GP if you are unsure. For urgent help call NHS 111, or 999 in an emergency.

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