Metformin Hydrochloride Medley 1000 mg prolonged release tablets – patient leaflet, side effects, dosage

1. What Metformin tablets are and what they are used for

The name of your medicine is Metformin Hydrochloride Medley prolonged release tablets which will be referred to as “Metformin tablets” throughout this leaflet.

Metformin tablets contain the active ingredient metformin hydrochloride which belongs to a group of medicines called biguanides, used in the treatment of Type 2 (non-insulin dependent) diabetes mellitus.

Metformin tablets is used together with diet and exercise to lower the risk of developing Type 2 diabetes in overweight adults, when diet and exercise alone for 3 to 6 months have not been enough to control blood glucose (sugar). You are at high risk of developing Type 2 diabetes if you have additional conditions like high blood pressure, age above 40 years, an abnormal amount of lipids (fat) in the blood or a history of diabetes during pregnancy.

This medicine is particularly effective if you are aged below 45 years, are very overweight, have high blood glucose levels after a meal or developed diabetes during pregnancy.

Metformin tablets are used for the treatment of Type 2 diabetes when diet and exercise changes alone have not been enough to control blood glucose (sugar). Insulin is a hormone that enables body tissues to take glucose from the blood and to use it for energy or for storage for future use. People with Type 2 diabetes do not make enough insulin in their pancreas 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 cause a number of serious long-term problems so it is important that you continue to take your medicine, even though you may not have any obvious symptoms. Metformin tablets make the body more sensitive to insulin and helps return to normal the way your body uses glucose.

This medicine is associated with either a stable body weight or modest weight loss.

Metformin tablets are specially made to release the drug slowly in your body and therefore are different to many other types of tablet containing metformin.

Polycystic ovary syndrome (PCOS) is a health condition that affects a woman’s hormone levels, menstrual cycle, and ability to have children. Metformin tablets is used in women with PCOS to stimulate ovulation (release of an egg from the ovaries), and subsequently the chance of getting pregnant, alone or together with other treatment options.

2. What you need to know before you take Metformin tablets

Do not take Metformin tablets if:

• you are allergic to metformin or to any of the other ingredients of this medicine (listed in section 6). An allergic reaction may cause a rash, itching or shortness of breath.
• you have liver problems
• you have severely reduced kidney function
• 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.
• you have lost too much water from your body (dehydration). Dehydration may lead to kidney problems, which can put you at risk for lactic acidosis (see ‘Warnings and precautions’).
• you have a severe infection, such as an infection affecting your lung 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’).
• you have been treated for acute heart problems or have recently had a heart attack or have severe circulatory problems or 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’).
• you are a heavy drinker of alcohol.
• you are under 18 years of age.

Warnings and precautions

Risk of lactic acidosis

Metformin 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 (see further information below), 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).

If any of the above apply to you, talk to your doctor for further instructions.

Stop taking Metformin 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.

Stop taking Metformin 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.

Talk to your doctor promptly for further instructions if:

• You are known to suffer from a genetically inherited disease affecting mitochondria (the energy-producing 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.

Surgery

If you need to have major surgery you must stop taking Metformin tablets during and for some time after the procedure. Your doctor will decide when you must stop and when to restart your treatment with this medicine.

Kidney function

During treatment with Metformin tablets, 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.

Elderly

If you are older than 75 years, treatment with Metformin tablets should not be started to lower the risk of developing type 2 diabetes.

Diet

You should continue to follow any dietary advice that your doctor has given you and you should make sure that you eat carbohydrates regularly throughout the day.

You may see some remains of the tablets in your stools. Do not worry- this is normal for this type of tablet. Other medicines and Metformin 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 tablets before or at the time of injection. Your doctor will decide when you must stop and when to restart your treatment with Metformin tablets.

Tell your doctor 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 tablets. It is especially important to mention the following:

• Medicines which increase urine production (diuretics (water tablets) such as furosemide).
• 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)
• Steroids such as prednisolone, mometasone, beclometasone.
• Sympathomimetic medicines including epinephrine and dopamine used to treat heart attacks and low blood pressure. Epinephrine is also included in some dental anaesthetics.
• Medicines that may change the amount of Metformin tablets in your blood, especially if you have reduced kidney function (such as verapamil, rifampicin, cimetidine, dolutegravir, ranolazine, trimethoprim, vandetanib, isavuconazole, crizotinib, olaparib).

Metformin tablets with alcohol

Avoid drinking too much alcohol while taking Metformin 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.

Women of childbearing potential

Metformin tablets can stimulate ovulation (release of an egg from the ovaries), in women who do not ovulate properly. Beware of an increased chance of becoming pregnant when using this medicine.

Driving and using machines

Metformin tablets taken on its own does not cause ‘hypos’ (symptoms of low blood sugar or hypoglycaemia, such as faintness, confusion and increased sweating) and therefore should not affect your ability to drive or use machinery.

You should be aware, however, that taking Metformin tablets with other antidiabetic medicines can cause hypos, so in this case you should take extra care when driving or operating machinery.

Metformin tablets contain sodium

This medicine contains less than 1mmol sodium (23mg) per dosage unit, that is to say it is essentially ‘sodium free’.

3. How to take Metformin tablets

Always take this medicine exactly as your doctor has told you. Check with your doctor or pharmacist if you are not sure.

Your doctor may prescribe Metformin tablets for you to take on its own, or in combination with other oral antidiabetic medicines or insulin.

Swallow the tablets whole with a glass of water, do not chew.

Recommended dose

Usually you will start treatment with 500 mg Metformin tablets daily. After you have been taking Metformin tablets for about 2 weeks, your doctor may measure your blood sugar and adjust the dose. The maximum daily dose is 2000 mg of Metformin tablets.

Normally, you should take the tablets once a day, with your evening meal.

In some cases, your doctor may recommend that you take the tablets twice a day. Always take the tablets with food.

Use in patients with kidney problems

If you have reduced kidney function, your doctor may prescribe a lower dose.

Polycystic ovary syndrome (PCOS)

The usual dose is 1500-2000 mg metformin hydrochloride taken once a day with the evening meal. You should check with your doctor or pharmacist when to stop taking the medicine.

If you take more Metformin tablets than you should

If you take extra tablets by mistake do not worry, but if you have unusual symptoms, contact your doctor. If the overdose is large, lactic acidosis is more likely. Symptoms of lactic acidosis are non-specific, such as vomiting, bellyache with muscle cramps, a general feeling of not being well with severe tiredness, and difficulty in breathing. Further symptoms are reduced body temperature and heart beat. If you experience some of these symptoms, you should immediately seek medical attention, as lactic acidosis may lead to coma. Stop taking Metformin tablets immediately and contact a doctor or the nearest hospital straightaway.

If you forget to take Metformin tablets

Take it as soon as you remember with some food. Do not take a double dose to make up for a forgotten dose.

If you stop taking Metformin tablets

Do not stop taking this medicine without speaking to your doctor.

If you have any further questions on the use of this medicine, ask your doctor.

4. Possible side effects

Like all medicines, this medicine can cause side effects, although not everybody gets them.

The following serious side effects may occur:

Metformin tablets may cause a very rare but very serious side effect called lactic acidosis (see section ‘Warnings and precautions’). If this happens, stop taking the Metformin tablets and contact a doctor or the nearest hospital immediately, as lactic acidosis may lead to coma.

Metformin tablets may cause abnormal liver function tests and hepatitis (inflammation of the liver) which may result in jaundice. If you develop yellowing of the eyes and/or skin contact your doctor immediately.

Other side effects

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

• diarrhoea,
• nausea,
• vomiting,
• stomach ache
• loss of appetite

If you get these, do not stop taking the tablets as these symptoms will normally go away in about 2 weeks. It helps if you take the tablets with or immediately after a meal.

Common (may affect up to 1 in 10 people):

• Taste disturbance.
• 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)
• 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):

• skin rashes including redness, itching and hives.

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 Website: 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.

5. How to store Metformin tablets

Keep this medicine out of the sight and reach of children.

Do not use this medicine after the expiry date that is printed on the pack after “EXP:”. The expiry date refers to the last day of that month.

This medicinal product does not require any special storage conditions.

Do not throw away 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.

6. Contents of the pack and other information

What Metformin tablets contain

• The active substance is metformin hydrochloride. Each prolonged release tablet contains 500, 750 or 1000 milligrams of metformin hydrochloride.
• The other ingredients are carmellose sodium (9000 cps), hypromellose (100000 cps), hypromellose (5 cps), colloidal anhydrous silica and magnesium stearate.

What Metformin tablets look like and contents of the pack

The 500 milligram tablets are White to off white, capsule shaped tablets, approximately 17.20mm in length and 8.10mm in width, debossed with “500” on one side and plain on the other side.

The 750 milligram tablets are White to off white, capsule shaped tablets, approximately 19.00mm in length and 9.30mm in width, debossed with “750” on one side and plain on the other side.

The 1000 milligrams tablets are White to off white, oval shaped tablets, approximately 22.00mm in length and 10.50mm in width, debossed with “1000” on one side and plain on the other side.

Metformin 500 mg and 1000 mg prolonged release tablets are supplied in PVC/PVDC and aluminium foil blister packs of 28 and 56 tablets.

Metformin 750 mg prolonged release tablets are supplied in PVC/PVDC and aluminium foil blister packs of 28, 56 or 84 tablets.

Not all pack sizes may be marketed.

Marketing Authorisation Holder and Manufacturer

Medley Pharma Limited

Unit 2A, Olympic Way,

Sefton Business Park, Bootle,

Merseyside, L30 1RD,

United Kingdom

This leaflet was last revised in December 2025

Other sources of information

To request a copy of this leaflet in large print, braille, please call +441515214527

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Product Name Reference Number

Metformin Hydrochloride Medley 500 mg prolonged release tablets

Metformin Hydrochloride Medley 750 mg prolonged release tablets

Metformin Hydrochloride Medley 1000 mg prolonged release tablets

PL 43870/0082 PL 43870/0083 PL 43870/0084