Patient leaflet - Metformin Hydrochloride Perennial 500 mg prolonged-release tablets
1. What Metformin Hydrochloride Prolonged-release Tablets is and what it is used for
Metformin Hydrochloride 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 Hydrochloride Prolonged-release 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.
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 Hydrochloride Prolonged-release Tablets 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 Hydrochloride Prolonged-release Tablets makes the body more sensitive to insulin and helps return to normal the way your body uses glucose.
Metformin Hydrochloride Prolonged-release Tablets is associated with either a stable body weight or modest weight loss.
Metformin Hydrochloride 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.
Polycystic ovary syndrome (PCOS) is a health condition that affects a woman's hormone levels, menstrual cycle, and ability to have children. Metformin Hydrochloride Prolonged-release 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 Hydrochloride Prolonged-release Tablets
Do not take Metformin Hydrochloride Prolonged-release 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 Hydrochloride Prolonged-release 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 Hydrochloride Prolonged-release 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 Hydrochloride Prolonged-release 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.
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.
If you need to have major surgery you must stop taking Metformin Hydrochloride Prolonged-release Tablets during and for some time after the procedure. Your doctor will decide when you must stop and when to restart your treatment with Metformin Hydrochloride Prolonged-release Tablets.
During treatment with Metformin Hydrochloride Prolonged-release 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.
If you are older than 75 years, treatment with Metformin Hydrochloride Prolonged-release Tablets should not be started to lower the risk of developing type 2 diabetes.
You may see some remains of the tablets in your stools. Do not worry - this is normal for this type of tablet.
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.
Do not stop taking this medicine without speaking to your doctor.
Other medicines and Metformin Hydrochloride Prolonged-release Tablets
If you need to have an injection of a contrast medium that contains iodine into your bloodstream, in the context of an X-ray or scan, you must stop taking Metformin Hydrochloride Prolonged-release Tablets before or at the time of injection. Your doctor will decide when you must stop and when to restart your treatment with Metformin Hydrochloride Prolonged-release 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 Hydrochloride Prolonged-release 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, beclomethasone
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 Hydrochloride Prolonged-release Tablets in your blood, especially if you have reduced kidney function (such as verapamil, rifampicin, cimetidine, dolutegravir, ranolazine, trimethoprim, vandetanib, isavuconazole, crizotinib, olaparib).
Metformin Hydrochloride Prolonged-release Tablets with alcohol:
Avoid excessive alcohol intake while taking Metformin Hydrochloride Prolonged-release 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 Hydrochloride Prolonged-release 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 Metformin Hydrochloride Prolonged-release Tablets.
Driving and using machines
Metformin Hydrochloride Prolonged-release 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 Metformin Hydrochloride Prolonged-release Tablets taken with other antidiabetic medicines can cause hypos, so in this case you should take extra care when driving or operating machinery.
Metformin Hydrochloride Prolonged-release Tablets contains Sodium
Each Metformin Hydrochloride Perennial Pharma 500 mg, 750 mg and 1000 mg Prolonged-release Tablet contains less than 1 mmol sodium (23 mg) per tablet, that is to say essentially ‘sodium free’.
3. How to take Metformin Hydrochloride Prolonged-release Tablets
Your doctor may prescribe Metformin Hydrochloride Prolonged-release Tablets for you to take on its own, or in combination with other oral antidiabetic medicines or insulin.
Always take Metformin Hydrochloride Prolonged-release Tablets exactly as your doctor 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 milligrams Metformin Hydrochloride Prolonged-release Tablets daily. After you have been taking Metformin Hydrochloride Prolonged-release Tablets for about 2 weeks, your doctor may measure your blood sugar and adjust the dose. The maximum daily dose is 2000 milligrams of Metformin Hydrochloride Prolonged-release Tablets.
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.
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 Hydrochloride Prolonged-release Tablets 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 Hydrochloride Prolonged-release Tablets immediately and contact a doctor or the nearest hospital straightaway.
If you forget to take Metformin Hydrochloride Prolonged-release Tablets
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, Metformin Hydrochloride Prolonged-release Tablets can cause side effects, although not everybody gets them.
The following side effects may occur:
Metformin Hydrochloride Prolonged-release Tablets 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 Metformin Hydrochloride Prolonged-release Tablets and contact a doctor or the nearest hospital immediately, as lactic acidosis may lead to coma.
Metformin Hydrochloride Prolonged-release Tablets 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 (affects more than 1 person in 10):
- Diarrhoea, 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 (affects less than 1 person in 10, but more than 1 person in 100):
- 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 (affects less than 1 person in 10,000):
- Skin rashes including redness, itching and hives.
Reporting of side effects
If you get any side effects, talk to your doctor or 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 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.
5. How to store Metformin Hydrochloride Prolonged-release Tablets
Keep Metformin Hydrochloride Prolonged-release Tablets out of the sight and reach of children.
Do not use them 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.
Medicines should not be disposed of via wastewater or household waste. Ask your pharmacist how to dispose of medicines no longer required. These measures will help to protect the environment.
6. Contents of the pack and other information What the tablets contain
Each prolonged-release tablet contains 500, 750, 1000 milligrams of the active ingredient metformin hydrochloride.
The other ingredients are
500mg: Magnesium stearate, carmellose sodium, hypromellose (K100M).
750 mg: Magnesium stearate, copolymer methcrylic acid-ethyl acetate (1:1) dispersion 30%, macrogol 6000, povidone (K90), carmellose sodium, hypromellose (K100M).
1000mg: Magnesium stearate, povidone, carmellose sodium, hypromellose (K100M).
What Metformin Hydrochloride Prolonged-release Tablets looks like and contents of the pack
The 500 milligram tablets are white to off white capsule shaped, biconvex, beveled edge tablet, with occasionally mottled appearance, debossed with " 001" on one side and plain on other side. The tablets are approximately 18 mm in length, 9 mm in width and 6 mm in thickness.
The 750 milligram tablets are white to off white capsule shaped, biconvex, uncoated tablet plain on both sides. The tablets are approximately 18 mm in length, 9 mm in width and 7.3 mm in thickness. The 1000 milligram tablets are white to off white oval shaped, biconvex, bevelled edge, uncoated tablet, debossed with “089” on one side and plain on other side. The tablets are approximately 22 mm in length, 11.5 mm in width.
Metformin Hydrochloride Prolonged-release Tablets is supplied;
Blister packs of 14, 20, 28, 30, 50, 56, 60, 84, 90, 100, 112, 120, 180, 600 Prolonged-release Tablets
Marketing Authorisation Holder
Perennial Pharma Ltd.
Titan Court, 2nd Floor,
3 Bishop Square,
Hatfield,
AL10 9NA,
United Kingdom
If you would like this leaflet in a different format or register a complaint, please contact the Marketing Authorisation holder listed above.
This leaflet was last revised in August 2026.
Useful tips
- If you smoke, try to stop
- Take regular exercise
- Drink as little alcohol as possible
- Look after your feet. Ask about this at the surgery or hospital
- Carry a card, bracelet or disk saying you are diabetic
Visit your diabetic clinic regularly
Manufacturer
GMP Manufacturing Ltd.
Park Royal House and Marfleet House, Valletta Street,
Hull,
HU9 5NP,
United Kingdom
PERPMET8011V1