Patient leaflet - Metformin Hydrochloride Relonchem 500 mg prolonged release tablets
1. What Metformin PR is and what it is used for
Metformin PR prolonged release tablets contain the active ingredient metformin hydrochloride and belong to a group of medicines called biguanides, used in the treatment of Type 2 (non-insulin dependent) diabetes mellitus.
Metformin PR 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.
The 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 PR is 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 PR makes the body more sensitive to insulin and helps return to normal the way your body uses glucose.
Metformin PR is associated with either a stable body weight or modest weight loss.
Metformin PR Prolonged Release Tablets are specially made to release the drug slowly in your body and therefore are different to many other types of tablet containing metformin.
2. What you need to know before you take Metformin PR
Do not take Metformin PR 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, diarrhea, 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').
Metformin PR with alcohol
Avoid excessive alcohol intake while taking Metformin PR 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 or pharmacist 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 PR taken on its own does not cause ‘hypos’ (symptoms of low blood sugar or hypoglycemia, 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 Metformin PR taken with other antidiabetic medicines can cause hypos, so in this case you should take extra care when driving or operating machinery.
3. How to take Metformin PR
Your doctor may prescribe Metformin PR for you to take on its own, or in combination with other oral antidiabetic medicines or insulin.
Always take this medicine exactly as your doctor or pharmacist has told you.
You should check with your doctor or pharmacist if you are not sure.
Swallow the tablets whole with a glass of water, do not chew.
Recommended dose
Usually you will start treatment with 500 mg Metformin PR daily. After you have been taking Metformin PR for about 2 weeks, your doctor may measure your blood sugar and adjust the dose. The maximum daily dose is 2000 mg of Metformin PR.
If you have reduced kidney function, your doctor may prescribe a lower dose.
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.
If you take more Metformin PR than you should
If you take extra tablets by mistake you need 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 PR immediately and contact a doctor or the nearest hospital straightaway.
If you forget to take Metformin PR
Take it as soon as you remember with some food. Do not take a double dose to make up for a forgotten dose.
4. Possible side effects
Like all medicines, this medicine can cause side effects, although not everybody gets them. The following side effects may occur:
Metformin PR may cause a very rare (may affect up to 1 user in 10,000) but very serious side effect called lactic acidosis (see section ‘Warnings and precautions’). If this happens, you must stop taking the Metformin PR and contact a doctor or the nearest hospital immediately, as lactic acidosis may lead to coma.
Metformin PR may cause abnormal liver function tests and hepatitis (inflammation of the liver) which may result in jaundice (may affect up to 1 user in 10,000). If you develop yellowing of the eyes and/or skin contact your doctor immediately.
Other possible side effects are listed by frequency as follows:
Very common side effects (may affect more than 1 in 10 people):
Diarrhea, nausea, vomiting, stomach ache or 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 side effects (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) 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 side effects (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 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 PR
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 the Metformin PR tablets contain
Each prolonged release tablet contains 500 mg, 750 mg or 1000 mg of metformin hydrochloride. The other ingredients are hypromellose, povidone, colloidal anhydrous silica, magnesium stearate and film-coating component – Opadry (OY-7300, containing Hypromellose, Titanium Dioxide and Propylene Glycol).
What Metformin PR looks like and contents of the pack
500 mg: White, Oval shaped, (approx.18.10 mm × 10.00 mm), film-coated tablets, debossed “MT” on one side and “500” on other side.
750 mg: White, oval shaped, (approx. 19.10 mm × 10.60 mm), film-coated tablets, debossed “MT” on one side and “750” on other side.
1000 mg: White, oval shaped, (approx. 20.20 mm × 11.40 mm), film-coated tablets, debossed “MT” on one side and “1000” on other side.
Metformin PR is supplied in packs of 28 or 56 tablets in blister strips composed of Alu/PVC-PVDC Blister.
Not all pack sizes may be marketed.
Marketing Authorisation Holder and Manufacturer
Relonchem Limited, Cheshire House,
Gorsey Lane, Widnes, Cheshire,
WA8 0RP, UK.
Metformin Hydrochloride Relonchem 500 mg Prolonged Release Tablets –PL 20395/0409
Metformin Hydrochloride Relonchem 750 mg Prolonged Release Tablets –PL 20395/0410
Metformin Hydrochloride Relonchem 1000 mg Prolonged Release Tablets –PL 20395/0411
This leaflet was last revised in July 2025.
If you would like this leaflet in a different format please contact the licence holder at the above address.
210 mm
210 mm