Metformin - oral

Patient Medicine Information
Why do I need this medicine?
Metformin is used to treat type 2 diabetes (long-term condition in which the body gradually becomes resistant to the effects of insulin or the pancreas does not produce enough insulin).

This medicine helps treat your diabetes by keeping your blood sugar under control.

Some extended-release preparations of Metformin may also be used to lower the risk or delay the onset of type 2 diabetes in people at high risk for developing the disease, including overweight adults or those with abnormal glucose levels.

Metformin is meant to be taken as part of a complete diabetes care programme that should include exercise, a healthy diet and regular monitoring of blood sugar levels.
How do I take this medicine?
Take Metformin exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by your doctor.

Metformin is available as a conventional tablet, extended-release tablet or oral solution.

If you are taking the conventional tablet, swallow it whole with a glass of water.

If you are taking the extended-release type of tablet (usually labelled as “ER”), swallow it whole. Do not divide, chew or crush the tablet.

If you have been given the oral solution, use the measuring cup or dosing syringe provided to measure your dose.

Take this medicine together with food or immediately after a meal. Try to take it at the same time each day.

Metformin must be taken regularly for it to be effective. Continue taking this medicine even when you feel better. Do not stop taking it unless instructed by the doctor.
What should I do if I have forgotten to take this medicine?
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and return to your normal dosing schedule.

DO NOT double a dose under any circumstances.

If you often forget to take your medicine, let your doctor and pharmacist know.
When should I not use this medicine?
Alert your doctor if you have the following conditions:
  • metabolic acidosis (a condition in which the body produces too much acid)
  • conditions that may alter kidney function e.g. dehydration, severe infection, shock
  • unstable heart failure
  • recent heart attack
  • lung problems e.g. respiratory failure, blockage of lung artery
  • severe blood loss
  • gangrene (death of body tissue due to a lack of blood flow, infection, illness or injury)
  • inflammation of the pancreas
  • severe kidney disease
  • excessive alcohol intake or alcohol addiction
  • liver disease
as Metformin may not be suitable for you.

If you are going for certain procedures involving the injection of a dye (iodinated contrast agents), inform your doctor that you are taking this medicine.
What should I take note of while taking this medicine?
Inform your doctor if you have the following conditions:
  • risks factors for lactic acidosis (build-up of lactic acid in the blood)
  • stable long-standing heart failure
  • abnormally high level of nitrogen waste products in the blood
  • mild to moderate kidney disease
  • type 1 diabetes
Let your doctor know if you are pregnant or breastfeeding.

Be sure to check with your doctor or pharmacist before giving Metformin to a child or elderly person. Children and elderly people may be more sensitive to the side effects.

If you are going for an operation, including minor surgery and dental work, inform your doctor or dentist that you are taking Metformin.

If you are taking Metformin with other types of oral anti-diabetic medicines, you may have been warned about hypoglycaemia (low blood sugar). This medicine itself does not usually cause hypoglycaemia, but it may increase the hypoglycaemic effect of other oral anti-diabetic medicines.

How do I know if I am experiencing hypoglycaemia?

Hypoglycaemia is the medical term for low blood sugar. Symptoms of hypoglycaemia include dizziness, tremor, shaky hands, feeling hungry, weak or confused, sweating. These signs are your body’s way of warning you that your blood sugar level is low.

It is important to recognise these symptoms and get relief for hypoglycaemia quickly, as the hypoglycaemia may worsen.

What should I do if I am experiencing hypoglycaemia?

Always carry some glucose tablets (also known as dextrose tablets) with you. Take 15 grams of glucose tablet at the first sign of hypoglycaemia, wait for 15 minutes and re-check your blood sugar level. If you are not feeling better or if your blood sugar level is still low (less than 4 mmol/L or 70 mg/dL), take another 15 grams of glucose tablet.

If you don’t have glucose tablets, you may take any of the following:
  • 1/2 cup (120 mL) of juice or regular soda (not diet)
  • 1 tablespoon of sugar, honey, or corn syrup
  • hard candies, jellybeans, or gumdrops (not sugar-free)
Get medical help should symptoms did not improve after the second serving.

Why is it important to keep my appointments with the doctor?

Keep your appointments with your doctor. Your doctor needs to monitor your condition and check your response to the medication regularly.
  • Routine tests (e.g. urine, blood sugar level, liver and kidney functions) may be done while you are being treated with this medicine. Your doctor will advise you about how often you need to have these tests.
  • Other routine blood tests (e.g. vitamin B12 in the blood) may also be done if you are taking this medicine for a long period.
  • Regular monitoring of signs and symptoms of lactic acidosis may also be needed.
What side effects could I experience?
Metformin may cause any of the following side effects: nausea, vomiting, abdominal pain or discomfort, stomach wind, diarrhoea, indigestion, altered taste, loss of appetite, generalised weakness or lack of energy.

Some side effects may need immediate medical help. Alert your doctor quickly if you experience any of the following:
  • stomachache, muscle cramps, a general feeling of not being well, severe tiredness, difficulty breathing, and sleepiness
Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Can I take this with other medicines?
Do not take Metformin if you will undergo certain procedures involving iodinated contrast agents (dyes).

Inform your doctor and pharmacist if you are taking or using any of these medicines:
  • other medicines for diabetes e.g. glimepiride, repaglinide, insulin
  • acetazolamide (medicine to reduce increased pressure in the eye)
  • certain medicines for fits or seizures e.g. phenytoin, topiramate, zonisamide
  • cimetidine (medicine to treat certain conditions that are caused by excessive acidity in your stomach)
  • dolutegravir (medicine for HIV infection)
  • certain medicines for heart disease or high blood pressure e.g. ranolazine, verapamil, captopril, losartan
  • trimethoprim (antibiotic)
  • certain medicines for cancer e.g. crizotinib, olaparib, vandetanib
  • isavuconazole (medicine to treat fungal infection)
  • certain medicines to treat TB (lung infection known as tuberculosis) e.g. rifampicin, isoniazid
  • anti-inflammatory medicines
  • phenothiazines (medicine for mood disorders)
  • birth control pills
  • water pills or medicines for water retention e.g. furosemide, hydrochlorothiazide
  • medicines for thyroid disease
  • blood-thinning medicines e.g. warfarin
This list does not include all medicines that may interact with Metformin.

Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicines, supplements and medicines that you buy without a prescription.
What special dietary instructions should I follow?
Avoid alcohol.

It is important for you to maintain a healthy diet and weight in order to help keep your diabetes under control.

It may be helpful to discuss your diet plan with your doctor or dietitian to manage your weight and blood sugar levels.
How should I store this medicine?
Store in a cool, dry place away from the reach of children. Protect from light, heat, and moisture.

Medicines must not be used past the expiry date.

The oral solution should be used within 60 days after opening.
This information is independently developed by MIMS based on metformin - oral and is provided for your reference only. It is not a replacement for and should only be used in conjunction with full consultation with a licensed healthcare professional, the information provided by your pharmacist and/or the manufacturer of the medication. It may not contain all the available information you require and cannot substitute professional medical care, nor does it take into account all individual circumstances. Although great effort has been made to ensure content accuracy, we shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2024 MIMS. All rights reserved. Powered by
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